A  FLIGHT  AT  SUNSET.     THE  HANRIOT  MONOPLANE  IN  MID-AIR 


Monoplanes  and  Biplanes 


THEIR    DESIGN,    CONSTRUCTION 
AND    OPERATION 


The  Application  of  Aerodynamic  Theory  with  a 

Complete  Description  and    Comparison 

of  the    Notable  Types 


By* 

GROVER    CLEVELAND    LOENING.    B.Sc.,  A.M. 

M 


278    ILLUSTRATIONS 


OF  THE 

UNIVERSITY 


NEW    YORK: 
MUNN    C&    COMPANY,    Inc. 

1911 


Copyright  1911  by  Munn  <®,  Co.,  Inc. 


Entered  at  Stationers  Hall 

London,  England 

1911 


All  rights  reserved 


Printed  in  the  United  States 
by""  oTVlacgowan  C8,  Slipper 
30  Beekman  St.,  New  York 


PREFACE 


AVIATION  has  now  advanced  to  the  stage  where  a 
practical  exposition  of  the  subject  is  widely  de- 
manded. Many  so-called  "popular"  books  have 
been  written,  and  contain  much  that  attracts  the  attention 
of  the  average  man,  but  little  if  anything  that  appeals  to 
the  more  serious  student  of  the  subject.  On  the  other 
hand,  many  valuable  treatises  have  been  written,  but  of  so 
scientific  and  mathematical  a  nature  that  they  are  almost 
unintelligible  to  all  but  a  few  technical  men;  and  in  many 
cases  it  must  be  acknowledged  that  mathematics  often  lead 
to  conclusions  that  are  wholly  at  odds  with  the  actual 
results  of  practice. 

In  this  book,  therefore,  the  author  has  made  it  his  pur- 
pose to  present  the  subject  of  " the  aeroplane"  in  a  manner 
that  is  at  once  intelligible  and  of  interest  to  the  average 
man,  as  well  as  of  value  to  the  more  learned  student. 

Much  of  the  work  involved  in  the  writing  of  this  book 
was  done  in  fulfillment  of  the  requirements  for  the  degree 
of  Master  of  Arts  at  Columbia  University.  This  work, 
largely  in  the  nature  of  research,  was  under  the  direction 
of  Dr.  Charles  C.  Trowbridge,  of  the  Department  of  Phy- 
sics, to  whom  the  author  is  naturally  indebted  for  many 
valuable  suggestions  and  much  friendly  aid. 

The  author's  thesis  accepted  for  this  degree  was  pub- 
lished serially  in  the  Scientific  American  Supplement,  Nos. 
1816-1822,  inclusive,  and  forms  the  nucleus  of  this  work. 
But  the  progress  in  the  subject  is  so  rapid  that  more  than 
twice  as  much  new  matter  has  been  added. 

After  an  historical  introduction  in  which  the  inestimable 
value  of  the  work  of  Langley,  Lilienthal  and  Chanute  is 


217054 


Vlll  PKEFACE 

pointed  out,  the  design  of  aeroplanes  is  taken  up.  The 
theory  of  Aerodynamics  is  given  as  simply  and  completely 
as  possible,  and  the  fundamental  principles  are  every- 
where fully  explained  and  emphasized.  At  the  end  of  this 
section  is  given  a  complete  example  of  the  design  of  an 
aeroplane,  which  should  prove  of  particular  value  to  those 
actively  engaged  in  aeroplane  construction. 

The  monoplanes  and  biplanes  in  their  various  forms  are 
then  considered.  Detailed  descriptions  of  virtually  all  of 
the  present  successful  types  are  given,  supplemented  by 
photographs  and  diagrams  reproduced  to  the  same  scale, 
thus  at  once  enabling  a  graphic  comparison.  Many  of  the 
types  are  changed  from  time  to  time  and  the  data-  is  in  many 
cases  unreliable,  but  the  author  has  spared  neither  time 
nor  effort  to  render  this  section  as  exact  as  he  was  able  to. 
Were  the  leading  machines  here  described  not  to  remain 
substantially  the  same  for  years  to  come,  they  should, 
nevertheless,  prove  of  permanent  value  in  that  they  repre- 
sent distinct  types  with  which  concrete  results  were  first 
obtained. 

In  the  last  part  of  the  book,  the  leading  types  are  com- 
pared and  discussed,  and  from  the  results  of  actual  prac- 
tice conclusions  are  drawn,  enabling  the  lines  of  probable 
future  development  to  be  pointed  out.  This  section  will 
prove  of  interest  to  almost  every  one,  as  it  is  the  author's 
experience  that  the  knowledge  of  this  subject  possessed  by 
the  average  person  is  far  greater  than  most  writers 
suppose. 

The  numerous  tragic  and  in  many  cases  avoidable  acci- 
dents constitute,  probably,  one  of  the  greatest  detriments 
to  the  progress  of  aviation.  Their  causes,  and  as  far  as 
possible  with  the  meagre  knowledge  available,  the  means 
for  their  prevention,  are  considered  in  this  section ;  and  the 
fact  that  aviation  is  reasonably  safe  can  unquestionably  be 
concluded  therefrom. 


PREFACE  *  IX 

c* 

The  closing  chapter  of  the  book  deals  with  the  "variable 
surface  aeroplane ",  a  development  which  the  author  be- 
lieves to  be  the  next  great  step  forward  in  the  rapid  pro- 
gress of  aviation. 

The  author  wishes  also  to  express  his  appreciation  of 
the  valuable  favors,  information  and  assistance  which  he 
has  received  from  Prof.  Win.  Hallock  of  Columbia  Univer- 
sity, Prof.  Carl  Runge  of  Goettingen,  Mr.  Wilbur  Wright, 
Mr.  A.  M.  Herring,  and  Mr.  Ernest  L.  Jones,  editor  of 
"Aeronautics". 

The  kind  offices  of  Messrs.  Stanley  Y.  Beach  and  John 
J.  Ide  have  greatly  facilitated  the  author 's  work. 

Many  excellent  photographs  are  reproduced  by  permis- 
sion of  '  *  Flight ' ',  London. 

New  York  City.  April,  1911 


TABLE   OF  CONTENTS 

PART  I. 

THE  DESIGN  OF  AEROPLANES 

Historical  Introduction — Aerodynamic  Theory — Aeroplane  Cal- 
culations. 


CHAPTER  I. 

PAGE 

Introduction — The  work  of  Langley,   Lilienthal   and   Chanute 

and  their  influence  on  the  progress  of  Aviation 1-16 

CHAPTER  II. 

THE  RESISTANCE  OF  THE  AIR  AND  THE  PRESSURE  ON  NORMAL 
PLANES 

Variation  in  the  density.  Air  Pockets.  The  values  and  na- 
ture of  Air  Resistance  as  determined  by  various  experi- 
menters. Values  of  Air  Resistance  as  determined  by 
Rotating  Apparatus  and  Straight  Line  Motion.  Photo- 
graphs of  air-streams  on  normal  planes.  Numerical 
example.  References  17-34 

CHAPTER   III. 
FLAT  INCLINED  PLANES 

The  diagram  of  forces  on  a  flat  inclined  plane.  Newton's 
famous  Theorem.  Photographs  of  air-streams  passing  flat 
inclined  planes.  Values  of  the  pressure  on  such  planes 
and  the  formulae  of  various  investigators.  Numerical  ex- 
ample of  the  calculation  of  the  Pressure  on  a  flat  plane. 
Lift  and  Drift — its  meaning  and  significance.  Refer- 
ences .  35-44 


Xll  CONTENTS 

CHAPTER  IV. 

THE  PRESSURE  ON  CURVED  FLAXES 

PAGE 

The  conditions  of  Pressure  on  a  curved  plane.  Lilienthal's 
determination.  The  forces  on  a  curved  surface.  Photo- 
graphs of  air-streams  passing  curved  planes.  The  results 
of  other  investigators.  The  Ratio  of  Lift  to  Drift  on 
Curved  surfaces.  Its  higher  value,  compared  to  flat  sur- 
faces. Eiffel's  results.  Numerical  Examples.  Refer- 
ences    45-54 

CHAPTER  V. 
THE  FRICTION AL  RESISTANCE  OF  AIR 

Results   of  various   investigations.     Zahm's   experiments,   and 
•     Skin  Friction  Table.     Numerical  Examples.     References..       55-60 

CHAPTER  VI. 
THE  CENTER  OF  PRESSURE  ON  FLAT  AND  CURVED  PLANES 

The  work  of  Joessel,  Kummer,  and  Langley  on  flat  planes. 
Work  of  Rateau,  Eiffel  and  Prandtl  on  curved  surfaces. 
Variation  in  position  of  centre  of  pressure  with  changing 
incident. angle.  The  Distribution  of  Pressure  on  a  plane. 
References 61-66 

CHAPTER  VII. 

THE  EFFECT  OF  DEPTH  OF  CURVATURE  AND  ASPECT  RATIO  UPON 
THE  LIFT  AND  DRIFT  OF  CURVED  PLANES 

The  work  of  Prandtl  and  Eiffel.  Low  depth  of  curvature  for 
a  racing  machine.  High  aspect  ratio  for  high  efficiency. 
Reasons  for  this.  References 67-74 

CHAPTER  VIII. 
NUMERICAL  EXAMPLE  OF  THE  DESIGN  OF  AN  AEROPLANE 

Complete  determination  of  size,  shape  and  characteristics  of 
the  main  planes,  weight,  speed  and  angle  of  incidence 
assumed.  Rudder  Design.  Determination  of  Motive 
Power  and  Propeller  Summary 75-90 


CONTENTS  Xill 

PART  II. 

DETAILED  DESCRIPTIONS  OF  THE  NOTABLE  AEROPLANES 

CHAPTER  IX. 
INTRODUCTION 

PAGE 

Definitions  of  Terms 91-94 

CHAPTER  X. 
IMPORTANT  TYPES  OF  MONOPLANES 

Detailed  and  Illustrated  Descriptions  of  the  Antoinette,  Bleriot 
XL,  Bleriot  XI  2  bis.,  Bleriot  XII.,  Bleriot  "Aero-bus," 
Dorner,  Etrich,  Grade,  Hanriot,  Nieuport,  Pfitzner,  Pischof, 
R.  E.  P3  (1909),  R.  E.  P.  (1911),  Santos  Dumont,  Sommer, 
Tellier  and  Valkyrie 95-160 

CHAPTER  XI. 
PROMINENT  TYPES  OF  BIPLANES 

Detailed  and  Illustrated  Descriptions  of  the  Breguet,  Cody 
(1909),  Cody  (1911),  Curtiss,  Dufaux,  Dunne,  H.  Farman 
(1909),  H.  Farman  (Michelin),  Maurice  Farman,  Goupy, 
Neale,  Paulhan,  Sommer,  Voisin  (1909),  Voisin  (Trac- 
tor), Voisin  (Bordeaux),  Voisin  (Front  Control,  1911), 
Wright  (1909),  Wright  (Model  R),  Wright  (Model  B) . . .  161-246 

PART  III. 

COMPARISON  OF  THI:  TYPES 
Controlling  Systems — Accidents — The  Future. 

CHAPTER  XII. 
COMPARISON  OF  THE  PROMINENT  TYPES 

Discussion  of  the  advantage  and  disadvantages  of  the  various 
dispositions.  I. — Mounting.  II.— Rudders.  III. — Keels. 
IV. — Position  of  seats,  motor,  etc.  V. — Position  of  center 
of  gravity.  VI. — Transverse  Control.  VII. — Aspect  Ra- 
tio. VIII.— Incident  Angle.  IX.— Propellers.  X.— Struc- 
ture and  Size.  XL— Efficiency.  XIL— Speed  and  Flight..  247-278 


XIV  CONTENTS 

CHAPTER  XIII. 

CONTROLLING   APPARATUS. 

PAGE 

Detailed  and  Illustrated  explanations  of  the  controlling  sys- 
tems on  1.— The  Antoinette.  2.— Bleriot.  3. — Breguet. 
4.— Curtiss.  5. — Etrich.  6. — Farman.  7. — Hanriot.  8. — 
Wright  279-290 

CHAPTER  XIV. 
ACCIDENTS — SAFE  FLYING  LIMITED  BY  WIND  CONDITIONS. 

Different  ways  in  which  accidents  happen.  1. — Physical  in- 
ability of  the  aviator.  2. — Collisions  with  obstacles.  3. — 
Heavy  landing.  4. — Loss  of  equilibrium  in  turning.  5. — 
Sudden  failure  of  motive  power.  6. — Breakage  of  some 
part  in  mid-air.  7. — Sudden  dives  when  in  motor  flight. 
8. — Sudden  dives  to  ground  in  "volplaning."  9. — Tearing 
away  of  wings  in  mid-air,  when  about  to  turn  at  the  end 
of  a  dip.  Explanation  and  Discussion 291-318 

CHAPTER  XV. 
THE  VARIABLE  SURFACE  AEROPLANE 

Consideration  of  its  advantages.     Suggested  means  of  varying 

an  aeroplane  surface 319-323 


PART  I. 

THE  DESIGN  OF  AEROPLANES 

HISTORICAL    INTRODUCTION— AERODYNAMIC 
THEORY— AEROPLANE    CALCULATIONS 


INTRODUCTION 

CHAPTEK  I 

IN  HIS  immortal  "Rasselas,"  Dr.  Samuel  Johnson  says,  "instead 
of  the  tardy  conveyance  of  ships  and  chariots,  man  might  use 
the  swifter  migration  of  wings,  the  fields  of  air  are  open  to  knowl- 
edge, and  only  ignorance  and  idleness  need  crawl  upon  the  ground."' 
This  fanciful  prophecy  has  almost  been  realized  in  fact. 

Over  one  thousand  aeroplanes  have  successfully  flown,  covering 
an  aggregate  distance  of  at  least  150,000  miles.  The  inscrutable 
Sphinx  has  seen  the  aeroplanes  of  to-day  pass  and  re-pass,  majestic 
in  the  exactness  and  ease  of  their  flight.  Chavez,  in  one  of  the  most 
daring  flights  ever  made,  crossed  over  the  chasms  and 
snow-covered  peaks  of  the  Alps.  Exploits,  almost  as  thrilling,  have 
been  performed  by  a  score  of  other  aviators;  the  Pyrenees,  the  Irish 
Channel,  and  the  Hudson  Eiver,  are  but  a  few  of  the  scenes  of 
well-executed  achievements,  and  aeroplanes  have  been  flown  under 
weather  conditions  that,  formerly,  would  have  been  considered 
prohibitive. 

Throughout  the  past  year  aviators  have  exhibited  consummate 
skill,  as  well  as  a  courage  that  was  often  foolhardy,  in  mounting 
higher  and  higher,  until  finally  Hoxsey  had  attained  the  wonder- 
ful altitude  of  11,400  feet.  The  sight  of  these  human  birds,  hover- 
ing beyond  the  clouds,  like  Pascal's  famous  point,  "in  equilibrium 
in  the  infinite,"  is  truly  an  impressive  one. 

But  in  the  active  excitement  of  the  present,  the  work  of  the  early 
pioneers  must  not  be  lost  sight  of. 

Langley,  Lil'ienthal,  and  Chanute  have  contributed  so  largely  and 
so  well  to  the  progress  of  aviation,  that  practical  aeroplane  design- 
ers of  the  present  owe  them  a  debt  of  gratitude  that  can  hardly  be 
repaid. 

It  is  both  interesting  and  appropriate  to  sum  up  the  work 
done  by  these  three  great  pioneers,  and  point  out  the  effect  their 
labors  have  had  upon  the  highly  successful  efforts  of  the  Wrights, 
Bleriot,  Levavasseur,  and  their  contemporaries. 


2  MONOPLANES    AND   BIPLANES 

LANGLEY 

It  was  in  1887  that  Prof.  Langley  commenced  his  experiments 
in  aerodynamics,  the  results  of  which  led  him  to  theoretical  conclu- 
sions that  are  fundamental.  Largely  through  the  generosity  of  Mr. 
William  Thaw,  of  Pittsburg,  Prof.  Langley  was  enabled  to  construct 
his  famous  "whirling  table"  at  Allegheny,  Pa.  With  the  scientific 
thoroughness  and  exactness  that  had  characterized  his  previous 


TELEPHOTO   SNAPSHOT   OF    LANGLEY'S  MODEL   IN   PLIGHT 

The  two  propellers  at  the  rear  of  the  leading  planes  are  seen  in  rotation,  at 
either  side  of  the  motor.  At  the  rear  is  another  set  of  monoplane  surfaces. 
The  cruciform  tail  piece  was  practically  automatic  in  its  action  and  kept 
the  machine  on  a  straight  course. 

work  in  physics  and  astronomy,  Langley  set  vigorously  to  work  to 
investigate  the  problem  of  mechanical  flight. 

The  "whirling  table"  consisted  of  a  horizontal  rotating  arm,  at 
the  outer  end  of  which  were  carried  the  surfaces,  forms,  and  pro- 
pellers that  were  to  be  tested.  Almost  all  the  results,  of  pressure, 
velocity,  etc.,  were  recorded  automatically  by  means  of  ingenious 
electrical  devices.  The  actual  results  of  his  experiments  are  referred 


MONOPLANES    AND    BIPLANES  3 

to  in  full  elsewhere  in  this  work,  but  it  may  be  pointed  out  that,  un- 
questionably, his  greatest  contribution  to  the  knowledge  on  this 
subject  was  his  thoroughly  scientific  verification  of  the  fact,  that  the 
old  Xewtonian  theorem  on  the  pressure  of  air,  experienced  by  a 
surface  inclined  at  small  angles,  gave  results  that  were  almost 
twenty  times  too  small.  In  addition,  Langley  investigated  the  well- 


SAMUEL  PIERPONT  LANGLEY 


known  constant  Kf  and  obtained  a  value  nearer  the  correct  one  than 
any  of  his  predecessors.  He  also  determined  fully  the  variation  in 
position  of  the  center  of  pressure,  the  analysis  of  the  total  pressure 
on  a  surface  into  a  lifting  force  and  a  resisting  one,  the  effect  of 
"aspect  ratio,"  and  other  equally  important  and  valuable  matters; 
but  inasmuch  as  these  experiments  were  made  on  flat  surfaces,  their 
results  have  had  little  application  to  the  design  of  the  present-day 
aeroplane.  Langley  considered  the  actual  friction  of  the  air  negli- 


4  MONOPLANES    AND    BIPLANES 

gible,  and  this  is  the  only  important  characteristic  of  his  work 
that  is  open  to  question. 

Langley  had  an  illustrious  contemporary  in  Col.  Kenard,  the 
builder  of  the  first  successful  dirigible  balloon,  the  "La  France." 
who  experimented  exhaustively  on  planes,  propellers  and  shapes  of 
"least  resistance77  in  his  laboratory  near  Paris,  and  whose  results 
to-day  are  of  immense  value  to  designers  of  dirigible  balloons.  Max- 
im, Kress,  Dines,  Phillips,  and  Hargrave  followed  Langley,  and 


FALSE  START  OF  THE  LANGLEY  MAN-CARRYING  "AERODROME"   IN  1903 
This  machine  was  a  faithful  copy  of  the  successful  model. 

contributed  handsomely  to  the  progress  of  aerodynamics,  but  it  is 
in  the  character,  and  especially  in  the  presentation,  of  his  work 
that  Langley  stands  out  as  the  first  and  greatest  pioneer. 

In  1891,  after  the  completion  and  publication  of  his  "Experi- 
ments in  Aerodynamics,77  Langley  actively  began  the  construction 
of  flying  machines.  At  first  he  experimented  with  models  driven 
by  rubber  bands,  but  he  found  the  flights  too  short  and  erratic  to 
give  any  practical  results. 


MONOPLANES    AND    BIPLANES  5 

His  first  steam  motor-driven  ''model"  aerodrome  "No.  0,"  was 
then  constructed,  and  was  followed  by  "No.  1"  and  "No.  2"  driven 
by  compressed  air  and  carbonic-acid  gas  motors.  All  of  these 
failed  because  of  the  poor  character  of  the  motors.  The  next 
model,  "No.  3,"  was  built  stronger  and  was  more  successful.  The 
propellers  were  tested  in  the  shop,  being  attached  to  a  pendulum 
device.  This  pendulum,  resting  on  knife  edges,  was  prolonged 


THE  WRECKED  "AERODROME"  IN  THE  POTOMAC  RIVER 
The  motor  and  some  details  of  the  framing  are  clearly  shown  here. 

aoove  the  points  of  support,  and  was  counterbalanced  to  give  in- 
different equilibrium.  The  propellers  were  so  mounted  that  the 
line  of  thrust  passed  through  the  center  of  gravity,  and  when 
power  was  applied,  they  lifted  the  pendulum,  thus  enabling  the 
dead-lift  power  of  the  engines  to  become  known. 

The  engines  of  "No.  3"  lifted  30  per  cent  of  their  own  weight. 
"No.  4"  was  then  built  and  taken  to  the  Potomac  on  a  house-boat, 


O  MONOPLANES    AND    BIPLANES 

to  be  extensively  tested.  Great  difficulties  were  experienced  in 
launching,  and  it  was  found  that  the  upward  pressure  of  the  air 
deflected  the  wings,  this  minute  difference  causing  the  planes  to 
act  badly. 

In  1894  and  1895  "No.  5"  and  "No.  6,"  stronger  and  better 
machines,  were  constructed. 

Finally,  on  May  6th  and  November  28th,  1896,  Langley's  best 


TOWING  THE  WRECKED  "AERODROME"  BACK  TO  THE  HOUSEBOAT 


model,  driven  by  a  1  horse-power  steam  engine  and  weighing  27 
pounds,  was  successfully  flown  several  times;  the  best  flight  was 
over  three-quarters  of  a  mile  long,  and  conclusively  demonstrated 
the  saneness  and  excellence  of  his  work. 

The  United  States  government  then  made  an  allotment  of  $50,- 
000  to  Langley  for  the  construction  of  a  man-carrying  aerodrome, 
which  was  finally  completed  and  tried  on  October  ?th,  1903.  This 
aeroplane,  as  can  be  seen  from  the  photographs,  consisted  of  two 


MONOPLANES    AND    BIPLANES  7 

0 

sets  of  arched  monoplane  surfaces,  with  a  central  fuselage  and  a 
controllable  cruciform  tail  very  similar  to  that  on  the  present 
Breguet  biplane  (see  p.  163).  The  two  propellers  rotating  in 
opposite  directions  were  situated  back  of  the  front  planes,  and 
were  driven  by  a  light  50  horse-power  steam  engine,  designed  by 
Mr.  C.  M.  Manley. 

The  machine  would  undoubtedly  have  flown  had  not  an  un- 
fortunate breakage  in  the  launching  apparatus  occurred,  just  as 
the  aerodrome  took  to  flight,  causing  it  to  lose  its  equilibrium 
and  plunge  downward  into  the  water.  Mr.  Manley,  who  was 
on  the  machine,  was  rescued  unhurt,  but  the  aerodrome  was 
so  badly  wrecked  that  no  further  experiments  could  be  conducted 
with  it.  A  section  of  the  press  then  took  a  hostile  attitude,  and 
succeeded  in  discouraging  Congress  from  any  further  appropria- 
tions. The  public  in  general  looked  upon  this  wreck  as  conclusive 
evidence  of  the  impracticability  of  Langley's  work,  and  the  bril- 
liant investigator  finally  died  three  years  later,  broken  in  heart 
by  the  unjust  criticisms  of  his  noble  efforts. 

As  aviation  progresses,  however,  the  great  worth  of  his  work 
becomes  more  and  more  manifest,  and  few  now  hesitate  to  give  to 
him  the  enormous  credit  that  is  his  due. 

The  effect  of  Langley's  labor  has  been  more  pronounced  on 
the  theory  of  flight  than  on  actual  practice.  The  general  lines 
of  some  of  the  French  monoplanes,  nevertheless,  especially  those 
with  large  lifting  tails,  closely  resemble  his  machine,  and  one  of 
M.  Bleriot's  first  successful  monoplanes  was  a  "Langley  type." 

LILIENTHAL 

What  Langley  did  to  advance  the  aerodynamics  of  flat  sur- 
faces, Otto  Lilienthal  did  for  arched  surfaces.  But,  in  addition,  this 
great  German  pioneer  launched  himself  into  the  air  on  wings, 
and,  from  his  personal  experiences,  laid  down  the  first  great 
laws  of  practical  flight,  as  we  know  it  to-day.  The  work  of  Lilien- 
thal has  without  doubt  had  permanent  effect  on  actual  flying,  and 
it  is  certain  that  without  it  we  would  not  have  progressed  so  fast. 


8 


MONOPLANES    AND    BJ  PLANES 


The  results  of  his  experiments  on  arched  surfaces,  obtained  by 
him  in  conjunction  with  his  brother,  after  years  of  quiet  scientific 
study  and  experiment,  were  published  in  1889  in  his  monumental 
work  "Der  Vogelflug  als  Grundlage  der  Fliegekunst." 

Lilienthal  early  recognized  the  importance  of  investigating  the 
flight  of  birds,  and  the  results  of  his  experiments  as  well  as  the 
important  discoveries  he  made  are  fully  treated  of  later. 


OTTO  LILIENTHAL* 

To  develop  his  theories  and  gain  the  experience  he  desired,  Lili- 
enthal  constructed  numerous  gliding  machines.  80  to  170  square 
feet  in  area,  in  which  he  launched  himself  into  the  face  of 
the  wind  from  the  top  of  a  mound  of  earth  at  Lichterfeld  near 
Berlin.  From  a  height  of  over  100  feet  he  glided  down  for  a  dis- 
tance of  609  to  1,000  feet,  landing  gently  at  the  bottom  of  the 
hill.  In  all  he  made  over  two  thousand  flights,  and  was  the  first 
man  in  the  world  to  remain  in  the  air  on  a  heavier-than-air  appara- 
tus for  any  considerable  length  of  time.  He  flew  at  first  without 
any  motive  power,  and  succeeded  in  deviating  his  direction  of 


MONOPLANES    AND    BIPLANES  9 

flight  to  the  right  or  left  merely  by  altering  the  position  of  his 
center  of  gravity  by  a  corresponding  movement  of  his  legs,  which 
were  dangling  freely  from  the  seat.  Later,  as  he  became  more 
and  more  expert  in  the  art  of  keeping  his  equilibrium,  he  built 
and  flew  a  double-deck  machine  equipped  with  a  2~y$  horse-power 
engine,  by  the  aid  of  which  he  could  feebly  flap  the  wings,  thus 
greatly  extending  the  lengths  of  his  glides.  At  this  promising 
stage,  August,  1896,  an  unexpected  calamity  removed  him  from 


LlLIENTHAL    IN    FREE    FLIGHT    ON    HlS    BlPLANE 

APPARATUS,  SHOWING  THE  CHARACTER  DF 

THE  FRAMEWORK  AND  SHAPE  OP  THE 

PLANES,  AS  WELL  AS  THE  REAR 

TAIL  PIECE 

The  equilibrium  was  preserved  by  the  swinging 
of  the  legs. 

his  sphere  of  work.  While  testing  a  horizontal  steering  arrange- 
ment fixed  on  an  old  and  well-worn  machine,  he  suddenly  fell 
from  a  height  of  50  feet,  and  broke  his  spine,  a  tragic  martyrdom 
which  later  impressed  so  forcibly  the  two  ingenious  Wright  brothers 
of  Dayton,  Ohio,  that  they  resolved  to  follow  in  his  footsteps,  and 
if  possible  perfect  the  flying  machine.  In  1896  Pilcher  in  Eng- 


10  MONOPLANES  AND  BIPLANES 

land,  and  Herring  in  America,  built  Lilienthal  type  gliders  and 
flew  them  successfully. 

Lilienthal's  greatest  contribution  to  the  advance  of  flight  was 
his  suggestion  and  proof  of  the  fact  that  "as  a  due  preparation 
for  eventual  human  flight,  practice  in  gliding  flight,  without  the 
use  of  a  motor,  constitutes  the  best  beginning/7 

CHANUTE 

Octave  Chanute,  who  early  achieved  a  remarkable  reputation  in 
his  profession  of  civil  engineering  serving  at  one  time  as  Chief  En- 
gineer of  the  Erie  Eailroad,  turned  his  attention  to  the  problem 
of  flight  in  his  later  years.  In  1894  Chanute  contributed  to  the 
literature  on  the  subject  his  interesting  work,  "Progress  in  Flying 
Machines."  about  the  most  complete  historical  treatise  on  aviation 
ever  written.  He  concluded  from  his  investigations  that  equili- 
brium was  the  most  important  problem  to  solve,  and  suggested 
that  the  simplest  way  to  obtain  it  was  by  movement  of  the  surfaces, 
and  not  of  the  man. 

Inspired  by  the  example  of  Lilienthal,  he  began  to  experiment 
in  1896,  and  the  first  machine  to  be  tried  out  on  the  shores  of 
Lake  Michigan  was  a  Lilienthal  type,  built  by  his  assistant,  Mr. 
A.  M.  Herring,  who  had  already  experimented  with  two  similar 
machines.  After  about  one  hundred  glides  had  been  made,  the 
equilibrium  was  found  so  precarious  and  so  difficult  to  control  that 
the  machine  was  pronounced  dangerous  and  discarded.  A  month 
later  Lilienthal's  sad  death  came  to  confirm  this  decision.  About 
the  same  time  a  "multiple-winged"  machine  was  tested  in  about 
three  hundred  glides.  On  this  machine  the  planes  could  be 
made  to  swing  to  and  fro  horizontally,  thus  enabling  the  posi- 
tion of  the  center  of  pressure  with  respect  to  the  center  of  gravity 
to  be  changed.  After  a  few  more  experimental  machines,  the 
famous  Chanute  " double-decker"  was  constructed  and  successfully 
tested.  This  machine  was  the  direct  prototype  of  the  present-day 
biplane,  and  embodied  in  its  construction  for  the  first  time  the 
bridge  truss  of  wood  braced  bv  steel  wires  which  is  to-dav  so 


MONOPLANES  AND  BIPLANES  •        11 

widely  used.  Some  seven  hundred  glides  were  made  with  this 
apparatus,  and  it  is  of  immense  importance  to  point  out  that 
not  the  slightest  accident  occurred  during  any  of  Chanute's  ex- 
periments. 

Before   the    end   of   the   century    Chanute's    experiments    were 


r 


% 


BB 


CHANUTE  GLIDER  STRUCK  BY  A  SIDE  GUST  ;  THE  BODY  SWING- 
ING OVER  TO  THE  RIGHT  SlDE    (OF  THE  PHOTOGRAPH) 

TO  RESTORE  EQUILIBRIUM 

taken  up  by  the  Wright  brothers,  to  whom  he  freely  gave  his  as- 
sistance and  valuable  advice.  In  the  summers  of  1900  and  1901 
the  Wrights  proceeded  to  follow  the  suggestion  of  Lilienthal  that 
practice  is  the  key  to  the  secret  of  flying,  and  in  the  numerous 
glides  executed  at  Kill  Devil  Hill,  North  Carolina,  they  grad- 
ually, and  with  infinite  skill,  made  themselves  masters  of  the 
air.  The  early  Wright  gliders  greatly  resembled  the  Chanute 
machines  in  construction,  but  differed  in  that  a  movable  elevation 
control  was  placed  in  front,  and  the  wings  were  made  warpable 


12 


MONOPLANES  AND  BIPLANES 


for  transverse  control.     The  aviator  lay  prone  on  the  lower  plane, 
thus  materially  reducing  head  resistance. 

Finally   on  December   17th,    1903,   the   first   prolonged   motor- 
driven  aeroplane  nights  were  made.    The  machine  used  at  this  time 


THE  HERALD  OF  A  NEW  ERA 
A  Wright  aeroplane  in  flight  at  dawn. 


by  the  Wrights  measured  40  feet  in  spread,  weighed  700  pounds 
with  the  operator,  and  was  equipped  with  three  propellers,  two  at 
the  rear  and  one  below  the  plane  to  assist  in  lifting.  The  pro- 
pellers were  driven  by  a  four-cylinder  16  horse-power  gasoline  mo- 
tor weighing  152  pounds.  The  speed  attained  in  the  four  short 


f] 

MONOPLANES  AND  BIPLANES 


13 


flights  made  was  about  30  to  35  miles  per  hour,  and  the  longest 
time  in  the  air  was  59  seconds. 

All  during  1904  short  practice  flights  were  made  at  Dayton, 
often  resulting  in  more  or  less  serious  breakages.  On  October  14th, 
1904,  three  flights  of  over  4,000  feet  were  made. 


BLEBIOT  DRIVING  THE  "No.  VIII  TER,"  ON  His  18-MiLE  TRIP 

FROM  TOURY  TO  ARTENAY,  FRANCE,  OCT.  31,  1908 

The  movable  ailerons  and  the  rudders  at  the  rear  are  shown 
in  this  photograph. 

'Another  machine  was  built  in  1905,  embodying  several  im- 
provements suggested  by  the  practice  of  preceding  years.  Finally 
on  October  5th,  1905,  the  Wright  biplane  flew  a  distance  of  24  1/5 
miles  in  38  minutes.  The  world  hesitated  to  believe  that  such 


14  MONOPLANES  AND  BIPLANES 

a  thing  was  possible,  and  for  a  long  time  the  Wrights  were  re- 
garded skeptically  by  many  people.  The  stimulating  effects  that 
Chanute's  experiments  and  help  had  on  the  work  of  the  Wrights,  as 
well  as  the  adoption  by  them  of  his  bridge-truss  type  of  construc- 
tion, are  unmistakable. 

About  this  time,  abroad,  Archdeacon,  Bleriot,  Pelterie.  and  Fer- 
ber,   following   also   in  the   stex  3   of   Chanute,  conducted   various 


FARMAN  IN  His  EARLY  VOISIN  BIPLANE,  MAKING  THE  FIRST 
CIRCULAR  FLIGHT  IN  EUROPE.,  JAN.  13,  1908 

gliding  experiments.  On  August  22nd,  1906,  Santos  Dumont,  by 
the  aid  of  a  remarkably  light  motor  designed  by  Levavasseur,  made 
the  first  motor  flight  in  Europe.  France  went  characteristically 
wild  with  enthusiasm,  placing  little  confidence  in  the  reported  ex- 
ploits of  the  Wrights.  At  once  the  Voisins,  with  Farman  and  Dela- 
grange,  began  the  development  of  their  machines,  and  Louis  Ble- 


MONOPLANES  AND  BIPLANES  15 

riot,  with  an  admirable  audacity  and  industry,  built  and  smashed 
monoplane  after  monoplane  until  he  had  evolved  the  highly  suc- 
cessful "Bleriot  VIII.,"  the  first  monoplane  in  the  world  to  make 
extended  trips. 

The  astonishing  progress  in  aviation  was  on,  and  as  it  rolls  and 
grows  in  size  like  the  proverbial  ball  of  snow,  we  should  pause 
and  reflect  upon  the  immense  value  of  the  work  of  Langley,  Lilien- 
thal,  and  Chanute. 


CHAPTEE  II. 

THE  RESISTANCE  OP  THE  AIR  AND  THE  PRESSURE  ON  XORMAL 
/  PLANES 

ALTHOUGH  the  fact  that  air  has  inertia  is  a  familiar  one,  the 
important  deductions  to  be  drawn  therefrom,  were  not  fully  rec- 
ognized until  the  classic  experiments  of  Langley  exhibited  them 
in  their  true  import. 

The  resistance  of  the  air  in  its  bearing  upon  aeronautics,  and 
especially  in  the  consideration  of  the  pressure  on  the  surface  of 
an  aeroplane,  is  of  fundamental  importance. 

Many  values  and  methods  of  determining  air  resistance  have 
been  suggested,  but  they  differ  widely  from  each  other.  Because 
of  this,  designers  of  aeroplanes  experience  great  difficulty  in  cal- 
culating the  probable  performance  of  their  machines.  A  small  dif- 
ference in  the  value  of  the  "constant  of  air  resistance"  may  mean 
an  over  or  under  estimation  of  a  certain  pressure  to  the  extent 
of  several  pounds,  which  in  turn  may  involve  added  expense  and 
decreased  efficiency. 

It  is  therefore  desirable  to  investigate  the  present  knowledge 
on  the  subject,  not  so  much  for  the  purpose  of  theoretic  dis- 
cussion as  to  arrive  at  some  definite  and  conclusive  values  of  the 
various  quantities  involved,  that  will  be  of  use  to  the  engineer. 

The  resistance  of  the  air  is  directly  proportional  to  its  den- 
sity. The  density  of  the  air  varies  with  (1)  temperature,  (2) 
pressure,  and  (3)  its  state  of  equilibrium. 

An  increase  of  temperature  causes  air  to  expand,  and  therefore 
the  density  diminishes.  Roughly,  the  density  of  the  air  varies  in- 
versely by  0.36  per  cent  for  a  difference  of  1  deg.  C. 

At  sea  level  in  our  latitudes  and  at  0  deg.  C.  1  cubic  foot  of  air 


18  MONOPLANES  AXD  BIPLANES 

weighs  very  nearly  iy2  ounces  if  the  pressure  is  at  760  milli- 
meters of  mercury.  But  this  pressure  decreases  as  the  height  above 
sea  level  increases,  and  also  at  any  point  is  subject  to  great  varia- 
tions due  to  meteorological  conditions.  A  difference  in  pressure 
of  7.6  millimeters  causes  a  direct  variation  of  the  density  of  about 
1  per  cent.  At  20  deg.  C.  a  difference  in  height  of  340  feet 
above  sea  level  gives  a  difference  of  10  millimeters  in  the  pressure. 
At  a  height  of  about  18,000  feet,  for  instance,  the  density  of  the 
air  is  exactly  one-half  of  that  at  sea  level. 

It  is  only  recently  that  the  effect  of  the  condition  of  equilibrium 


AN  INSTANTANEOUS  PHOTOGRAPH  BY  PROP. 

MAREY,  SHOWING  THE  ACTION  OF  AN 

AIR  STREAM  PASSING  A  NORMAL 

SURFACE  FROM  LEFT  TO  RIGHT 

Note  the  whirls  and  regions  of  discontinuity 
and  the  compression  of  the  air  stream  in 
front  of  the  surface.  These  marvelous  photo- 
graphs were  obtained  by  admitting  thin 
streams  of  smoke  into  the  air  current. 

of  the  air  at  any  one  point  upon  the  density  has  been  considered. 
The  temperature  and  the  pressure  in  a  certain  region  remaining 
constant,  a  gusty  wind  and  several  buildings,  e.tc.,  being  in  the 
neighborhood,  there  would  be  large  variations  in  the  density 
at  different  points.  The  disturbances  and  eddies  set  up  by  normal 
planes,  spheres  and  spindles,  are  clearly  shown  in  the  accompanying 
stream  line  photographs.  Even  an  aeroplane  with  an  arched  surface 
will,  if  the  speed  is  high  enough,  leave  a  region  of  high  density 
below  and  in  its  wake,  and  a  region  of  low  density  above  and  in 
its  wake.  Everywhere  in  the  atmosphere,  and  especially  on  windy 
days,  there  exist  "pockets"  of  high  density  and  of  low  density, 
sometimes  large  enough  to  completely  immerse  a  full-sized  aero- 


I 

MONOPLANES  AND  BIPLANES  19 

plane.  Very  often  the  nature  of  a  country  is  such  that,  when  the 
wind  comes  from  a  certain  direction,  a  region  of  low  density  al- 
ways forms  at  some  particular  point.  Abroad  at  the  Eheims 
aerodrome,  and  here  at  our  flying  grounds  at  Mineola,  such  points 
actually  exist,  always  about  in  the  same  place,  and  are  called  by 
the  aviators  "air  holes."  An  aeroplane  entering  one  of  these  low- 
density  regions  from  the  air  of  higher  density  around  it,  will  sud- 
denly fall  without  any  warning,  merely  because  the  pressure  has 


THE  ACTION  OF  A  STREAM  OF  WATER  PASSIXG  A  NORMAL 
SURFACE  FROM  LEFT  TO  RIGHT.    (AHLBORN) 

enormously  decreased,  and  the  aeroplane  has  not  had  time  to  at- 
tain the  requisite  velocity  of  support  in  this  lighter  medium.  Then 
again,  when  the  machine  after  this  experience  passes  into  the 
heavier  surrounding  air,  the  shock  due  to  the  suddenly  increased 
pressure  is  likely  to  cause  a  straining  of  some  part,  and  a  possi- 
ble breakage.  Whenever  considering  the  air  in  which  an  aero- 
plane is  flying,  we  must  never  lose  sight  of  the  fact  that  this 
fluid  is  irregular  and  unstable  in  its  flow,  subject  to  the  most  in- 
tricate movements  and  treacherous  to  the  last  degree. 

The  density,  therefore,  varies  greatly,  and  directly  affects  the 
pressures  on  an  aeroplane.    In  the  summer,  on  a  dry  clear  day,  the 


MONOPLANES  AND  BIPLANES 


high  temperature  causes  a  low  density,  and  the  pressure  is  light, 
so  that  the  aeroplane  experiences  the  least  resistance,  and  therefore 
at  this  season  travels  at  a  higher  speed.  On  the  other  hand,  in 
winter,  with  "snow  in  the  air,"  the  density  is  greatest,  thus 
enabling  the  aeroplane  to  carry  a  much  heavier  load.  Alti- 
tude will  tend  to  give  a  speed  increase,  and  rainy  weather  an 
increase  of  weight-lifting  capacity. 

Whatever  value  of  air  resistance  is  laid  down,  consequently,  must 
be  taken  with  reserve,  as  it  is  subject  to  very  wide  variations. 


NEWTON'S  IDEA  OF  THE  ACTION  OF  THE  AIR 

The  particles  of  air  striking  directly  against  a  surface  placed  normal  to  the  air 
stream,  AB  representing  a  section  of  the  surface. 

Values  of  air  resistance  vary  also  with  the  form  of  the  body,  and 
some  shapes  called  "shapes  of  least  resistance,"  "fusiform,"  or 
"stream  line  form,"  often  experience  only  half  the  resistance  of  an 
equivalent,  flat  surface,  placed  normal  to  the  air  current.  Only  flat 
normal  surfaces  are  considered  here  because  they  give  the  maximum 
resistance. 

Sir  Isaac  Newton,  in  Section  VII,  Bk.  11,  of  the  Principia, 
treats  "of  the  motion  of  fluids,  and  the  resistance  made  to  pro- 
jected bodies."  He  defines  air  as  an  elastic,  non-continued,  rare 
medium,  consisting  of  equal  particles  freely  disposed  at  equal  dis- 
tances from  each  other. 


MONOPLANES  AND  BIPLANES 


21 


Thus  if  we  represent  by  A  B  the  section  of  a  surface  against 
which  a  stream  of  air  is  flowing,  then  the  particles  of  air,  according 
to  Newton,  impinge  directly  against  the  surface,  as  indicated  by  the 
small  arrows  in  the  diagram  on  p.  20. 

In  contrast  to  this  Newton  defines  water,  quicksilver,  oil,  etc., 
as  continued  mediums,  where  all  the  particles  that  generate  the 
resistance  do  not  immediately  strike  against  the  surface.  The  sur- 
face is  pressed  on  only  by  the  particles  that  lie  next  to  it,  which 
particles  in  turn  are  pressed  on  by  the  particles  beyond,  and  so 
on.  The  diagram  below  shows  the  character  of  this  fluid  pres- 
sure. 


DIAGRAM  OF  THE  FLOW  OF  AIR  AROUND  A   NORMAL  SURFACE  AB 

The  subsequent  experiments  of  Bernouilli,  Euler,  Robins,  Borda, 
Bossut,  and  De  Buat  showed  the  imperfection  of  the  first  New- 
tonian theory.  That  air  as  a  medium  is  similar  in  character  to 
water  is  shown  conclusively  by  the  accompanying  photographic 
results  of  the  experiments  on  stream  lines  of  air  by  Marey. 

The  resistance  of  a  "continued"  medium  of  this  sort,  according 
to  Newton,  is  in  the  "duplicate  ratio  of  the  velocity"  and  directly 
as  the  density  of  the  medium.1 

Navier  derives  a  similar  relation.2 

Robins  in  1746,  with  a  view  to  determining  the  resistance  of 
the  air  to  cannon  balls,  whirled  planes  and  spheres  about  a  circu- 
lar orbit,  and  found  that  the  resistance  varied  directly  as  the 
square  of  the  velocity. 


22  MONOPLANES  AND  BIPLANES 

In  1791  Col.  Beaufoy  carried  on  a  series  of  experiments,  the 
results  of  which  were  published  later  in  connection  with  the  Swed- 
ish tests  of  Lagerhjelm  in  1811.  and  showed  also  that  the  pressure 
varied  as  the  square  of  the  velocity.3 

Eennie  in  1830  abundantly  verified  this  relation  for  low  velocity 
and  it  can  be  accepted  as  true.4 

In  other  words,  if  we  express  by  P  the  pressure  on  a  normal 
surface  of  area  S,  generated  by  an  air  stream  of  velocity  V,  then 
P=K  S  V2 '(1) 


THE  FLOW  OF  WATER  AROUND  AN  ELLIPTICAL  PRISM  FROM 
RIGHT  TO  LEFT.    (AHLBORN) 

where  K  is  a  constant  of  figure  involving  the  density  of  the  air 
and  depending  on  the  barometric  pressure,  the  temperature  and 
the  character  of  the  surface  and  usually  termed  the  "constant  of 
air  resistance." 

This  equation  may  be  derived  from  the  laws  of  mechanics. 

If  we  let  W^the  weight  of  air  directed  against  any  normal  sur- 
face in  a  given  time;  w=the  weight  in  pounds  of  one  cubic  foot 
of  air;  T7=the  velocity  of  the  air  stream  in  feet  per  second;  8= 
the  area  of  the  surface  on  which  the  pressure  acts;  J/=the  mass 
of  air  of  weight  W;  g=ihe  acceleration  due  to  gravity=32.2  feet 
per  second2;  and  P=the  pressure  on  the  area  8. 

Then  W=w  S  v 


OF -HE 

UNIVERSITY 

OF 


MONOPLANES  AND  BIPLANES  23 

Wv       w 

The  momentum  of  the  force  on  the  area  =  M  v  =  — = — S  v2 

9          9 

If  $=1  square  foot;  w=0.0807  pounds  per  cubic  foot  for  32 
deg.  F.  and  760  millimeters  barometric  pressure;  and  V  be  ex- 
pressed in  miles  per  hour,  then  since  P=M.v 

P  =  .0054  r2 

K  thus  taking  the  theoretical  value  0.0054,  where  V  is  expressed 
in  miles  per  hour  and  P  in  pounds  per  square  foot.  This  system 
of  units  will  be  used  throughout  this  discussion. 

In  1759  John  Smeaton,  in  discussing  some  experiments  of  Rouse, 
deduced  the  formula  P  =  0.005  S  V2,  and  considering  S  unity  he 
published  a  table  of  the  velocity  and  pressure  of  wind,  as  given 
here.5  The  correct  Smeaton  value  for  K  is  0.00492,  but  it  has  be- 
come customary  in  engineering  practice  to  take  it  as  0.005. 

Smeaton  adopted  this  table  in  his  paper  on  "Mills"  from  his 
friend  Rouse  without  any  explanation  of  the  kind  of  experiments 
from  which  it  had  been  formed. 

Rouse  had  based  his  results  on  a  statement  by  Mariotte,  which 
he  verified  by  his  own  experiment  consisting  of  whirling  a  3  square 
foot  plane  in  a  circular  orbit  of  only  30  feet  circumference  and 
.at  a  maximum  velocity  of  8  miles  an  hour.  Rouse  assuming  that 
the  resistance  varied  as  the  square  of  the  velocity,  laid  down  the 
law  that  P  =  0.005.  V2. 


SMEATON 

S   TABLE 

Velocity, 
Miles  per  Hour 

Pressure, 
Lbs.  per  Sq.  Ft. 

Velocity, 
Miles  per  Hour 

Pressure, 
Lbs.  per  Sq.  Ft. 

1 

.005 

40 

7.873 

2 

.020 

45 

9.963 

3 

.044 

50 

12.30 

4 

.079 

55 

14.90 

5 

.123 

60 

17.71 

10 

.492 

65 

20.85 

15 

1.107 

70 

24.10 

20 

1.968 

75 

27.70 

25 

3.075 

80 

31.49 

30 

4.429 

100 

49.2 

35 

6.027 

24 


MONOPLANES  AND  BIPLANES 


Smeaton,  although  misinformed  as  to  the  experiments  of  Ma- 
riotte,  proceeded  to  make  use  of  these  results  and  of  the  constant 
0.005  and  without  any  experiments  of  his  own,  formulated  the 
well-known  Smeaton  Table  (see  p.  23),  which  appears  as  standard 
in  the  engineering  textbooks  of  all  countries. 

Bender,  in  a  thorough  review  of  the  whole  subject,  says  that 
Smeaton's  table  is  certainly  unreliable.6 

Hutton  in  1787,  using  a  whirling  apparatus  similar  to  that  used 
by  Robins,  deduced  the  value  of  K  as  0.00426. 

The  experiments  of  Didion  on  falling  plates  of  11  square  feet, 
area  in  1837  established  K=3. 00336,  and  later  experiments  by 
him,  the  results  of  which  were  published  in  1848,  showed  con- 


Am  FLOWING  FROM  RIGHT  TO  LEFT  PAST  A 
CIRCULAR  PRISM  (MAREY) 

This  is  precisely  the  character  of  the  disturb- 
ance caused  by  a  rod  or  steel  tube  on  an 
aeroplane. 

clusively  that  the  resistance  of  the  air  was  directly  proportional 
to  the  square  of  the  speed.7 

Col.  Duchemin  in  1842  conducted  experiments  on  the  resistance 
of  fluids  which  are  in  many  ways  remarkable.  He  investigated  the 
subject  very  thoroughly  and  his  work  is  standard.  The  value  of 
K  he  derived  as  0.00492.8 

Poncelet,  who  also  did  much  work  in  this  line,  obtained  the  value 
of  ^=0.00275.9 

Hagen  in  1860  obtained  the  value  ^=0.0029/2,  and  Recknagel 
in  1886  got  the  value  0.00287.10  These  experiments  were  all 
thorough,  and  the  surfaces  were  moved  in  a  straight  line. 

Thibault  in  1856  and  Goupil  in  1884  derived  K=0.0053. 


MONOPLANES  AND  BIPLANES  25 

Lord  Rayleigh  also  considered  the  subject  theoretically  and  de- 
duced K  =  0.0055.12 

Experiments  similar  in  character  to  the  recent  ones  of  Eiffel 
were  conducted  in  1892  by  Cailletet  and  Collardeau  and  K  was 
found  to  be  0.0029.13 

Dr.  Pole  in  1881  deduced  7^=0.0025,  and  at  some  length  dis- 
cussed the  absolute  unreliability  of  Smeaton's  table.14 

Langley  in  his  experiments  with  the  rolling  carriage  in  1888 
obtained  values  of  K  ranging  from  0.00389  to  0.00320.15 

Col.  Eenard  of  the  French  army,,  the  builder  of  the  famous  di- 
rigible "La  France/'  carried  out  extensive  experiments  on  planes 
and  shapes  of  "least  resistance"  in  1887,  and  deduced  the  value  of 
JT=0.00348.16 

Canovetti  in  the  elaborate  experiments  conducted  by  him  on  in- 
clined railways  at  Brescia  and  Brunate  in  Italy  during  1901,  de- 
termined the  value  of  K  as  0.0029.17 

The  most  recent  and  complete  experiments  on  the  resistance  of 
the  air  were  conducted  by  Eiffel  in  1903  and  1905.  He  recognized 
two  sources  of  inaccuracy — the  neglect  of  the  consideration  of  the 
separate  air  filaments  which  vary  at  different  points  on  the  sur- 
face, and  the  cyclonic  motion  of  the  air,  due  to  a  revolving  source. 
The  experiments  were  conducted  on  the  Eiffel  tower,  and  the  sur- 
face was  attached  to  a  carriage  by  springs,  the  pressure  being 
recorded  on  a  blackened  cylinder.  The  carriage  was  allowed  to 
fall  vertically  about  312  feet,  and  was  constrained  in  its  motion  by 
a  vertical  cable. 

The  coefficient  K  varied  remarkably  little  and  was  practically  de- 
termined as  0.0031.18 

Many  other  values  of  K  have  been  determined. 

Prof.  Allen  Hazen  in  1886  deduced  ^=0.0034.19 

Dines  in  1889  obtained  the  value  0.0035.20 

Lilienthal'21  and  Von  Loessel22  determined  K  as  0.13  in  metric 
units  or  0.005  in  English  units. 

In  1890  C.  F.  Marvin  at  Mount  Washington,  N".  H.,  where  it  is 
said  winds  as  high  as  100  miles  per  hour  were  observed,  got  K 
as  0.004. 


2G 


MONOPLANES  AND  BIPLANES 


T.  E.  Stanton  determined  K  for  small  surfaces  at  0.0027.2:: 

The  Voisin  brothers,  builders  of  the  famous  biplane,  derived  a 
value  of  /iT=0.0025.24 

The  Wrights  in  1901  conducted  experiments  on  small  planes  and 
got  the  value  of  K  as  0.0033. 

Other  formula?  than  the  one  now  so  generally  in  use  (formula  I) 
have  been  suggested. 

Canovetti  lays  down  for  unit  surfaces  the  empirical  formula: 
P=0.0324  72-f  0.432  v   (in  metric  units)   as  a  result  of  his  ex- 
periments.23 

Experiments  conducted  by  Morin,  Piobert,  and  Didion  in  France 
about  1837  indicated  that 

p  =  0.0073  4-  0.0034  72 


THE  AIR  FLOW  PAST  A  CIRCULAR  SECTION, 
UNDER  DIFFERENT  LIGHT 

The  bright  regions  indicate  high  pressure  and 
the  dark  regions  as  at  the  rear  of  the  section 
indicate  rarefaction. 

Soreau  in  1902  proposed  -a  formula  which  for  small  velocities 
shows  the  pressure  to  vary  as  the  square  of  the  velocity  and  for 
higher  velocities  as  the  cube.26 

Eenard  had  previously  pointed  out  that  the  general  formula 

p=K  S  V2 
was  bad  for  either  very  low  or  very  high  velocities.27 

Zahm,  in  measuring  projectile  resistances,  found  the  pressure 
to  vary  as  the  cube  of  the  velocity  for  high  speeds.28 

Eiffel  found  that  between  18  and  40  meters  per  second  the  pres- 
sure was  proportional  to  the  square  of  the  velocity,  and  at  speeds 
above  33  meters  per  second  it  already  began  to  increase  and  vary 


MONOPLANES  AND  BIPLANES  27 

as  the  cube.  It  is  hardly  probable,  however,  that  aeroplanes  will 
ever  reach  velocities  where  the  pressure  will  vary  other  than  sen- 
sibly as  the  square. 

Interesting  experiments  conducted  by  A.  B.  Wolff  showed  that 
K  for  45  degrees  Fahr.  was  equivalent  to  Smeaton's  value,  that  at 
0  deg.  Fahr.  it  was  10  per  cent  greater,  and  at  100  deg.  Fahr. 
10  per  cent  less.29 

Langley,  in  considering  the  effect  of  temperature  on  density,  ex- 
presses the  relation  between  pressure  and  velocity  for  unit  surface 
in  the  form,  gy2 

P=  ''  1+0.00366 U— 10  deg.) 

where  0.0036G  is  the  coefficient  for  expansion  of  air  per  degree 
C.,£— temperature  of  the  air  in  degrees  C.,  and  K  is  expressed  for 
10  deg.  C.  in  metric  units. 

Prof.  Kernot  in  experiments  conducted  on  the  Forth  Bridge 
found  the  average  pressure  on  large  surfaces  such  as  railway 
coaches,  houses,  etc.,  never  exceeded  two-thirds  of  that  upon  a 
surface  of  1  or  2  square  feet.30  The  variable  density  of  air  puffs, 
whirls,  etc.,  would  account  for  this,  and  probably  the  maximum 
intensity  of  pressure  is  confined  to  small  areas. 

Borda,  Hutton,  and  Thibault  found  from  their  researches  that 
the  resistance  increased  with  the  absolute  size  of  surface,  while 
Dines  holds  a  contrary  opinion.  Von  LoessPs  experiments  showed 
that  small  and  large  surfaces  experience  resistances  simply  propor- 
tional to  their  sizes. 

Eiffel  found  that  K  increased  with  the  surface,  but  this  increase 
was  less  and  less  as  the  size  increased,  and  tended  toward  a  maxi- 
mum of  0.0033. 

Soreau,  after  investigating  the  subject,  gives  it  as  his  opinion 
that  K  may  vary  slightly  with  increase  of  size,  but  in  the  necessary 
approximations  that  are  made  in  aeroplane  design  such  variation 
would  be  negligible. 

Most  of  the  experiments  cited  thus  far  have  been  conducted  on 
planes  and  shapes  of  very  small  size,  and  show  large  discrepancies. 

The   method  of  experimenting  by  use  of  a  whirling  table  is 


28  MONOPLANES    AND  BIPLANES. 

unquestionably  inaccurate,  because  the  air  in  the  vicinity  of  the 
apparatus  is  itself  set  in  a  rotating  motion. 

Many  of  these  results,  therefore,  because  of  the  inadequate  char- 
acter of  the  apparatus  used  cannot  be  conclusively  applied  to  the 
case  of  an  aeroplane  in  flight. 

Those  experiments  conducted  in  a  straight  line,  however,  more 
nearly  resemble  the  actual  conditions,  and  it  need  hardly  be  pointed 
out  that  the  character  of  the  air  resistance  to  a  fast  moving  train 
resembles  much  more  the  resistance  experienced  by  a  full  sized 
aeroplane  in  flight,  than  any  other  of  the  methods  used. 


THE  AIR   PLOWING   BY  A   STREAM-LINE   FORM, 

SHOWING  THE  GREATER  EVENNESS  OP. 

FLOW,  AND  THEREFORE  DECREASE 

OF  RESISTANCE 

Numerous  and  excellent  experiments  on  the  resistance  to  trains 
have  been  conducted. 

Mr.  Scott  Kussell  as  early  as  1846,  in  discussing  the  resistance 
of  the  atmosphere  to  trains,  stated  that  the  results  of  his  experi- 
ments showed  that  the  pressure  according  to  Smeaton's  Table  was 
almost  double  the  actual  pressure  on  a  plane  and  that  the  formula 
P  =  0.0025  8  V2  was  correct.31 

In  1901  J.  A.  F.  Aspinall  in  experiments  on  trains  carefully 
measured  the  air  resistance  by  pressure  gages  and  found  A'=0.003. 
In  his  paper  on  this  subject  previous  experiments  are  discussed  very 
thoroughly,  and  in  the  fifty-five  different  formulae  and  experiments 
on  the  resistance  to  trains  that  he  cites,  the  large  majority  of  them 
make  use  of  values  of  K  below  0.003.32 

The  most  recent  and  accurate  results  in  this  line  are  given 
by  the  experiments  on  air  resistance  conducted  during  the  tests 


MONOPLANES  AND  BIPLANES  29 

of  the  high-speed  electric  trains  on  the  Berlin  Zossen  Railway  in 
1903.33 

The  velocities  attained  were  as  high  as  110  miles  an  hour,  and 
the  air  resistance  was  carefully  measured  by  an  elaborate  set  of 
accurate  pressure  gages. 

The  results  were  plotted  on  a  large  chart  and  the  mean  value 
of  the  observations  showed  that 

P=0.0027  S  V2. 

These  experiments  are  undoubtedly  the  most  accurate  and  the 
best  applicable  to  the  actual  conditions  of  a  large  body  moving 
through  the  air  at  high  speed,  that  have  ever  been  conducted,  and 
show  conclusively  that  the  values  of  air  pressure  as  originally 
formulated  by  Smeaton  are  very  seriously  at  fault. 

There  are  then  to  be  distinguished  two  main  methods  of  de- 
termining K,  one  by  a  rotational  apparatus,  and  the  other  by  move- 
ment in  a  straight  line. 

In  the  following  tables  experiments  according  to  these  two 
systems  are  separately  grouped,  and  the  values  given  are  weighted. 

Table  of  Values  of  K  as  Determined  by  Rotating  Apparatus 

Name.  Year.  Value. 

Rouse 1758  .00500 

Hutton   ..  .   1787  .03426 

Duchemin    1842  .00492 

Hazen    1886  .00340 

Renard ,  ..    1887  .00348 

Langley    .  .  .  .    1888  .00389 

Dines 1889  .00350 

Lilienthal 1889  .00500 

Marvin   1890  .00400 

Loessl    1899  .00530 

Mean   value =0.004275 

Mean  weighted  value.  .  .  .  ..=0.00421 


30  MONOPLANES  AND  BIPLANES 

Table  of  Values  of  K  as  Determined  by  Straight  Line  Motion 

Name.  Year.  Value. 

Didion    1837  .00330 

Poncelet    , 1840  .00275 

Russell   1846  .00250 

Hagen I860  .00292 

Pole 1881  .00250 

Eecknagel 1886  .00287 

Cailletet 1892  .00290 

Canovetti    .  .  . 1901  .00290 

Wright    .......................    1901  .00330 

Aspinall    .....................    1901  .00300 

Stanton    .... 1903  .00270 

Zossen    .......................    19-03  .00270 

Eiffel 1905  .00310 

Voisin 1907  .00250 

Mean   value .=0.00285 

Mean  weighted  value.  , =0.00290 

according  to  the  completeness  of  the  experiments,  the  accuracy, 
the  time,  whether  very  old  or  very  recent,  and  the  size  of  appara- 
tus used.  Mean  values,  and  weighted  mean  values  are  then  ob- 
tained. It  must  be  borne  in  mind  that  the  object  of  this  investi- 
gation is  to  derive  a  working  value  of  K  applicable  to  full  sized 
aeroplanes,  and  therefore  experiments  conducted  on  large  surfaces 
are  weighted  more  than  those  on  small  ones. 

Grouping  these  results  three  distinct  values  of  K  are  arrived  at: 

(1)  JT=0.0054     (By  theory). 

(2)  7T=0.0042      (By  rotational  apparatus). 

(3)  K =0.0029      (By  movement  in  a  straight  line). 

For  the  purposes  of  calculations  of  pressures  on  an  aeroplane 
value  (3)  is  unquestionably  the  most  correct  one. 

These  results  are  graphically  represented  in  Curve  1,  which 
shows  the  great  difference  in  the  theoretical  value  of  air  resist- 
ance and  value  (3)  very  strikingly. 

We  may  therefore  conclude  that  for  calculations  of  air  pressure 


MONO  FLAXES  AND  BIPLANES 


31 


as  applied  to  aeroplanes,  the  most  practical  expression  of  such  pres- 
sure is 

P00  =  0.003  8  V2 

where  K  =  0.003,  and  Pno  =  the  pressure  on  a  surface  of  area  S, 
normal  to  the  air  stream  of  velocity  V. 

Ordincifes-TVessures  in  tos.  ]er  sq.  fl. 


f"  N  ."• 

~o  ~o  "d. 


i?f'P| 

If  I  f   9 
-I?  z? 


32 


MONOPLANES  AND  BIPLANES 


An  examination  of  stream-line  photographs  similar  to  those  re- 
produced here,  reveal's  distinctly  the  fact  that  the  air  stream 
directed  against  a  normal  surface  is  deflected  at  an  angle,  varying 
with  the  conformation  of  the  surface.  In  the  diagram  below 
such  a  condition  of  air  flow  is  shown  in  an  exaggerated  manner. 
This  suggests  a  method  of  obtaining  a  rational  value  of  K,  by  al- 


M 


DIAGRAM  SHOWING  A  POSSIBLE  ACTION  OF  STREAMS  OF  AIR. 
MCA  AND  MC'B  ON  A  SURFACE  AB 

most  the  same  process  of  mechanics  as  that  used  in  deriving  the 
value  0.0054  if  the  primary  condition  there,  that  the  air  is  de- 
viated at  90  deg.  is  discarded. 

Instead,  as  we  see  by  the  diagram  above,  the  air  streams  are 
deviated  from  their  original  horizontal  direction  to  a  direction 
C'B  or  CA,  at  an  angle  C'BN,  which  in  many  instances  of  air-flow 
against  a  flat  normal  surface  may  be  as  low  as  45  deg. 

MCA  and  MC'B,  the  two  filets  of  air  when  suddenly  directed 


MONOPLANES  AND  BIPLANES.  33 

against  the  surface  AB,  are  likely  to  imprison  a  cushion  of  air 
ADB.  The  air  stream  presses  on  this  air  cushion  along  DB  and 
DA.,  and  causes  it  to  transmit  the  pressure  in  all  directions,  as  in 
any  fluid.  This  means  that  there  will  be  a  compression  in  the  air 
cushion  itself  along  the  region  DD ',  as  well  as  a  pressure  on  the 
surface  itself.  The  moving  air  stream  will  therefore  cause  pressure 
P  and  P'  to  act  normal  to  DA  and  DB,  and  in  addition  there  will 
be  a  resistance  due  to  the  internal  friction  of  the  fluid  along  DA 
and  DB.  But  in  no  case  do  we  have  a  moving  mass  of  air  strik- 
ing a  surface  at  90  deg.  to  its  line  of  motion.  The  fact  that  the 
hypothetical  surfaces  DA  and  DB  are  at  an  angle  of  inclination 
means  that  the  pressure  exerted  on  them  will  be  to  the  pressure 
considered  previously  for  the  90  deg.  normal  condition  (0.0054) 
as  the  sine  of  45  deg.  is  to  the  sine  of  90  deg.?  or  roughly,  as  0.71 
to  1.  Therefore  instead  of  the  theoretical  value  0.0054  we  would 
have  0.71X0.0054=0.0038,,  a  value  which  certainly  is  much  more 
reasonable. 

This  method  is  open  undoubtedly  to  question,  but  is  suggested 
here  as  a  line  of  investigation  that  holds  promise  of  bringing  theo- 
retical aerodynamics  more  easily  in  accord  than  any  other  with 
the  actual  results  of  experiment. 


1  Newton,   I.,    Principia,   Prop.   XXXVII.,   Bk.   II. 

2  Navier,   v.   11,   Mem  de  1'Inst.  de  France. 
3Beaufoy,     "Nautical    Experiments,"     London,     1834. 

4  Rennie,    "On   Resist,   of   Bodies   in   Air,"    Tran.    Roy.   Soc., 
1831,  p.   423. 

5  Chanute,  "Progress  in  Flying  Machines"  :   Rost,  F.,  "Flug- 
apparate"  ;   Kent,   p.   492. 

6  Bender,  Proc.  Inst.  Civ.  Eng.,  v.  69,  p.  83. 
7Didion,   M.,   "Traite  de  Balistique,"  Paris,   1848. 

8  Duchemin,   "Les  Lois  de  la  Resistance  des  Fluides." 

8  Poncelet,    "Mecanique   Industrielle,"  p.   601. 

10Recknagel,  "Uber  Luftwiderstand,"  Zeit.  Ver.  Deut.  Ing., 
1886. 

11  Goupil,    La    Locomotion   Aerienne,    1884. 

"Rayleigh,   "Resistance  of  Fluids,"  Phil.  Mag.,  1876. 

13Cailletet  and  Collardeau,   Comptes  Rendus,   1892. 

"Pole,  Proc.  Inst.  Civ.  Eng.,  v.  69,  p.  205. 

15  Langley,   "Experiments  in  Aerodynamics,"  p.   94. 

10Renard,  Ch.,  "Sur  ia  Resistance  de  1'Air,"  Rev.  de  1'Aero- 
nautique,  v.  2,  p.  31. 


34  MONOPLANES  AND  BIPLANES. 

17  Maleire,    E.,    Genie    Civil,    v.    51,    p.    245 ;    Canovetti,    C., 
Aerophile,  v.  10,  p.  140;  Sci.  AM.,  v.  96,  p.  171. 

18  Eiffel,    A.    G.,    "Recherches    sur    la    Resistance    de    1'Air," 
Paris,    1907 ;   Comptes   Rendus,   v.    137,   p.    30 ;    Aerophile,   v. 
17,  p.   5. 

19  Hazen,  A.,  Am.  Jour.  Sci.,  v.  134,  p.  241. 

20  Dines,  Proc.  Roy.  Soc.,  v.  48,  p.  252. 

21  Lilienthal,  O.,   "Der  Vogelflug,   als   Grundlage  der   Fliege- 
kunst."  Berlin,  1889. 

22  Ritter      v.      Loessl,      F.,      "Die      Luftwiderstand-gesetze." 
Vienna,  1895  ;  Zeit.  fur  Luft.,  v.  10,  p.  235. 

23  Stanton,  ±\  E.,  Proc.  Inst.  Civ.  Eng.,  v.  156,  p.  78. 
2*Voisin,  G.  and  C.,  "Sur  la  valuer  de  K,"  Rev.  de  1' Avia- 
tion," August   15th,   1907. 

25  Canovetti,  C.,  Paris  Acad.  Sci.,  v.  144,  p.  1030. 

20  Soreau,  R.,  "Nouvelle  loi  de  la  Resistance  de  1'Air,"  Soc. 
des  Ing.  Civ.,  p.  464,  v.  2,  1902. 

27Renard,  Ch.,  Sci.  AM.  SUP.,  v.  34,  p.  13819. 

28Zahm,  A.  F.,  "Resistance  of  the  Air." 

29  Wolff,  A.  R.,  "The  Windmill  as  a  Prime  Mover." 

!0Kernot,  Eng.  Rec.,  February  20th,  1894. 

81  Russell,  Scott,  Proc.  Inst.  Civ.  Eng.,  v.  5,  p.  288. 

82Aspinall,  J.  A.  F.,  "Train  Resistance,"  Proc.  Inst.  Civ. 
Eng.,  v.  147.  p.  155. 

38  Street  Railway  Journal,  v.  19,  p.  726, 


CHAPTER  III. 


FLAT  INCLINED  PLANES 

IF  a  thin  flat  plane  is  inclined  at  an  angle  a  above  the  horizontal 
(diagram  on  this  page),  and  if  this  plane  is  then  placed  in  a  cur- 
rent of  air  moving  at  a  velocity  V ' ,  as  indicated  by  the  arrow,  the 
air  stream  will  generate  a  force  Pa.  in  the  surface  tending  to  move 
it  in  the  direction  shown  on  Pa  (which  direction  is  always  per- 
pendicular to  the  plane  when  flat  surfaces  are  used). 


THE  FORCES  ON  A  FLAT  PLANE  IN  AN  AIR  CURRENT  OF 
VELOCITY  V,  AND  SET  AT  AN  ANGLE  OF  INCIDENCE  a 

D  is  overcome  by  the  thrust  of  the  propeller.  L,  the  lift  on 
the  planes  supports  the  weight.  P  is  the  total  effect  of  the 
aiv  pressing  on  the  surface  as  it  passes  by  it. 

In  Chapter  II,  the  pressure  P90,  acting  on  a  surface  placed  nor- 
mal to  the  air  stream  was  defined  and  its  value  KSV2  explained. 
When  the  plane  is  inclined,  this  pressure  then  called  P<a  is  greatly 
reduced  and  varies  with  the  angle  of  inclination.  It 
is  most  convenient  to  express  Pa  as  some  part  or  function  of  P90. 
The  ratio  of  P« /P  90  then  is  a  numerical  quantity,  by  which  P90 
is  multiplied  to  obtain  Pa. 

The  relation  of  the  pressure  of  a  fluid  on  an  inclined  face  to  that 


36 


MONOPLANES  AND  BIPLANES 


on  a  normal  face  was  first  investigated  by  Newton  in  Prop. 
XXXIV,  Bk.  II.  of  his  "Principia,"  and  he  treats  of  the  subject 
in  the  following  manner ;  see  diagram  on  this  page. 

Let  ABIK  represent  a  spherical  body  with  center  C.  Let  the 
particles  of  the  medium  impinge  with  a  given  velocity  upon  this 
spherical  body  in  the  direction  of  right  lines  parallel  to  AC.  Let 
GB  be  one  of  these  right  lines. 

In  GB  take  LB  equal  to  CB  and  draw  BD  tangent  to  sphere  at 
B.  Upon  K C  and  BD,  let  fall  the  perpendiculars  BE  and  LD. 
Then  a  particle  of  the  medium  impinges  on  the  globe  at  B  in  an 


NEWTON'S  THEOREM  ON  THE  PRESSURE  EXERTED  BY  AIR 
AGAINST  AN  INCLINED  SURFACE 


oblique  direction.  Let  this  force  with  which  it  would  strike  the 
globe  be  F.  A  particle  of  the  medium  impinges  on  the  face  of 
the  cylinder  ONJQ  described  about  the  globe  with  the  axis  A  Cl, 
in  a  perpendicular  direction  at  B.  Let  this  force  be  F1. 

Then  F  :  F1  =  LD  :  LB  =  BE  :  BC. 

The  force  F  tends  to  impel  the  globe  in  direction  BC,  normal 
to  BD.  Let  this  tendency  be  T.  And  let  the  tendency  of  the  force 
to  move  the  globe  in  direction  parallel  to  AC  be  T1. 

Then  T  :  T1  =  BE  :  BC. 

Then  joining  these  ratios  if  we  let  P=the  pressure  exerted  on 
the  globe  obliquely  in  the  direction  GB  and  P1=the  pressure  ex- 


MONOPLANES  AND  BIPLANES.  37 

erted  on  the  face  of  the  cylinder,  perpendicularly,  in  the  line  GB, 
P  :  V  =  BE'2  :  BC2. 

But  BE  is  the  sine  of  the  angle  BCE,  and  therefore  sine  of  angle 
LED,  which  is  the  angle  of  incidence  of  an  element  of  surface  to 
the  direction  of  the  wind.  We  therefore  have  by  the  Newtonian 
theorem,  that  the  pressure  of  a  moving  fluid  on  an  inclined  surface 
is  proportional  to  the  square  of  the  sine  of  the  angle  between  the 
surface  and  the  current. 

Navier  and  Weisbach  also  advanced  this  theory  with  the  result 
that  scientists  of  the  highest  repute  deduced  that  mechanical  flight 
was  practically  impossible. 


ACTION  OP  AN  AIR  STREAM  ON  A  FLAT  INCLINED  PLANE 

The  angle  of  incidence  is  the  angle  between  this 
plane  and  the  horizontal.  The  stream  is 
flowing  from  right  to  left. 

Actual  experiment,  however,  shows  that  this  is  absolutely  un- 
founded and  that  the  pressure  -on  an  inclined  surface  varies  sub- 
stantially as  the  sine  of  the  angle  of  incidence.  The  pressure  on 
the  inclined  surfaces  of  aeroplanes  in  use  to-day  is  over  20  times 
greater  than  Newton's  theorem  would  indicate,  and  the  difference 
is  more  pronounced,  the  smaller  the  angle. 

The  fundamental  hypothesis  of  Newton,  that  the  resistance  of 
the  air  was  due  directly  to  the  impact  of  the  particles  renders 
his  consideration  of  this  question  invalid. 

In  the  excellent  stream  line  photographs  of  Prof.  Marey,  re- 
produced herewith,  the  character  of  the  air  streams  about  an  in- 
clined flat  surface  are  distinctly  noticeable,  and  of  themselves 
refute  any  suppositon  that  air  acts  on  such  a  surface  di- 


38  MONOPLANES  AND  BIPLANES. 

rectly  by  impact.  In  the  detailed  study  of  photographs  of  stream 
lines  of  air.  there  is  no  doubt  an  opportunity  of  really  solving 
the  many  problems  of  aerodynamics,  and  any  number  of  valuable 
conclusions  can  be  drawn  directly  from  them.  For  example,  on 
close  examination  one  is  inclined  to  observe  that  any  form  of  sur- 
face is  continually  surrounded  by  a  thin  film  of  air,  and  that  the 
moving  air  stream  never  really  comes  in  contact  with  the  surface 
itself,  at  all. 

In  1763  Borda  conducted  some  experiments  on  flat  inclined  sur- 
faces, and  proposed  a  formula  in  which  the  pressure  was  made 
proportional  to  the  sine  of  the  angle  of  incidence. 

Shortly  after  this,  in  1788,  Hutton  measured  the  horizontal  com- 
ponent of  the  pressure  on  inclined  planes  by  means  of  a  small 
whirling  arm,  and  these  experimental  results  showed  distinctly  that 
Newton's  theory  was  at  fault.  Hutton  deduced  the  ratio  of  re- 
sistance between  inclined  and  normal  planes  where  a  =  angle  of 
inclination  as  sin  a  1.842  cos  af 

Col.  Duchemin  in  1842  proposed  the-  formula : 1 

-  «r 
2  sin  a 

P    —  P 

•L      n  —   •-*•    t 


110 


l-|-sin2(r 

where  Pa.  is  the  pressure  acting  on  a  plane  inclined  at  angle  a  with 
the  air  current,  and  P90  the  corresponding  pressure  on  the  same 
plane  when  placed  normal  to  the  current  as  obtained  by  the  formu- 
la: 

PW=KSV*  (see  Chapter  II) 
Hastings   proposed   the   formula: 

Pa  =  P1)0  2  sin  a 
for  small  angles. 

Lord  Rayleigh,  after  investigating  this  problem2,  expressed  the 
relation  between  P90  and  Pa  as 

P    --  P     „  (4  +  *)  sin  " 
4  +  *sin« 

This  formula  was  verified  by  Stanton  in  1902. 
-Combining  both  theory  and  experiment  in  Von  Loessl  made  the 


MONOPLANES  AND  BIPLANES. 


39 


Ordmotes  -  Ratio   of  £  to  f^-. 

Kj  L«  4k  O) 


VO  fe 


\ 


?\3 


A 


••2S?ff 


« 


.<>  PI    A 
S^g- 


£ 

s 


\\ 


II" 


ro 


40  MONOPLANES  AND  BIPLANES. 

pressure  on  an  inclined  surface  directly  proportional  to  the  sine  of 
the  angle  of  incidence.3 

De  Louvrie  enlarging  upon  the  formula  of  Duchemin,  expressed 
P  a  in  terms  of  P904,  in  the  form : 

.  2  sin  a  (I  +  cos  a 

Fa  —  -T»o    X : 

1  "T   COS  a  +   sin  a. 

Dorhandt  and  Thiesen  proposed  the  formula : 

2  sin  a   /         0.62  sin  a\ 
^a  ==      90  1  +  sm  aV  "  "  1  +  sin  a) 

Joessel's  formula  is: 

siii  a 


Pa   =    A 


90  0.39  +0.61  sin  a 
and  Goupil  gives 

Pa  =  Poo  (2  sin  a  —  sin2  a) 
Eiffel,  as  a  result  of  his  earlier  experiments   (1907),  obtained 

values  that  led  him  to  adopt  the  simple  formula  Pa  =    P»*  £- 

ou 

where  Pa  =  1,  when  a  =  30  deg. 
Luyties  also  suggests  the  formula : 

Pa  =  P»»  (2  sin  a  —  sin2o:.) 

which  gives  results  almost  identical  with  that  of  De  Louvrie.5  He 
further  gives  the  convenient  and  accurate  enough  relation  for  very 
small  angles,  proposed  by  Eiffel. 

A  formula  of  substantially  the  same  form  as  Hutton's  was  sug- 
gested by  Soreau  quite  recently.6 

Six  of  these  various  formulae  are  graphically  represented  in 
Curve  2,  the  difference  between  the  Newtonian  formula  and  the 
others  being  quite  marked. 

This  curve  can  be  used  precisely  as  a  table.  If,  for  example,  we 
desire  to  determine  the  pressure  on  a  flat  plane,  the  area  of  which, 
8  =  10  square  feet,  moving  at  V  =  30  miles  per  hour,  and  inclined 


MONOPLANES  AND  BIPLANES.  41 

at  an  angle  a  =  20  cleg.,  the  pressure  P,JO  is  first  computed. 
P00  =  0.003  X  8  X  F2 
=  0.003  X  10  X  900 
=  27  pounds. 

From  the  curve  we  see  that  a  reasonable  value  for  Pa/P90  when 
a  =  20  deg.,  is  about  0.6.    Then: 
P«=0.6P90 
=  0.6    X    27 
=  16.2  pounds: 

This  is  the  total  force  acting  on  this  surface  under  the  assumed 
conditions. 

Langley's  experiments  showed  conclusively  that  the  sine  squared 
law  was  wrong.  In  the  experiments  with  the  resultant  pressure 
recorder,7  his  results  show  a  remarkably  close  agreement  with  the 
formula  of  Duchemin,  as  is  shown  by  the  accompanying  Table. 
This  practically  identifies  Duchemin's  formula  as  correct  for  flat 
surfaces. 

TABLE  OF  VALUES  FOR 

Pa 

Ratio  of         —  ,  according  to  Langley  and  Duchemin 
P 

•*•   90 

Angle  of  By  Langiey's  By  Duchemin's 

Inclination.  Experiments.  Formula. 

5                                           .15  .17 

10                                          .30  .34 

15                                           .46  .48 

20                                           .60  .61 

25                                           .71  .72 

30                                          .78  .80 

35                                           .84  .86 

40                                           .89  .91 

45                                           .93  .94 

We  can  therefore  conclude  for  flat  surfaces  that 

2  sin  « 


where  /'.o  =  .003  5  V\ 


MONOPLANES  AND  BIPLANES. 


LIFT  AND  DRIFT 

If  we  represent  by  Pa  (see  diagram  on  p.  35)  the  pressure 
acting  perpendicular  to  the  surface  of  a  flat  plane,  inclined  at  an 
angle  a  in  a  wind  current  of  velocity  V ,  we  may  resolve  it  into  two 
components  at  right  angles,  one  acting  perpendicularly  and  equal 
to  L,  and  another  acting  horizontally  and  equal  to  D. 

Then  D  =  Pa  sin  a 
and  L  =  Pa  cos  a 

This  resolution  was  indicated  by  Sir  George  Cayley  as  early  as 
1809. 

It  is  not  purely  theoretical,  however,  but  has  been  verified  by 
Langley's  experiments  as  well  as  by  actual  practice. 

In  the  present  terminology  of  Aerodynamics  we  call  L  the  "lift" 


A  FLAT  PLANE  AT  A  HIGH  ANGLE  OF  INCIDENCE 

IMPEDING  THE  AIR  FLOW  FROM  RIGHT 

TO  LEFT 

and  D  the  "drift"  of  a  plane,  L  being  the  effective  supporting  force 
equal  to  the  weight  carried  and  D  the  dynamic  resistance  overcome 
by  the  thrust  of  the  propeller. 

The  velocity  of  the  aeroplane  is  directly  dependent  on  the  value 
of  D,  and  as  D  decreases,  the  resistance  to  motion  becomes  less  and 
consequently  either  the  power  necessary  decreases,  or  a  higher 
velocity  can  be  obtained. 

The  ratio  of  these  two  quantities  L/T),  called  the  ratio  of  lift  to 
drift,  is  obviously  an  excellent  means  of  expressing  the  aerodynamic 
efficiency  of  an  aerofoil,  and  is  used  as  such. 

Since  one  of  the  primary  considerations  in  aeroplane  design  is 
to  carry  the  greatest  amount  of  weight  at  the  highest  velocity,  or 


MONOPLANES  AND  BIPLANES.  43 

conversely  with  the  least  expenditure  of  power,  it  is  desirable  to 
obtain  as  high  a  value  for  the  lift  L  and  as  low  a  value  for  the  drift 
D,  as  possible.  In  other  words,  we  try  to  obtain  a  high  value  of 
L/D,  the  ratio  of  lift  to  drift. 

In  gliding  flight,  the  higher  the  value  of  L/D,  the  longer  will  be 
the  glide. 

1  Duchemin,  "Les  Lois  de  la  Resistance  des  Fluides,"  Paris, 
1842. 

2  Rayleigh,   Lord,  Manch.   Philos.   Soc.,   1900 ;   Nature,  v.  27, 
p.  534  ;  Smith.  Inst.  Rep.,  1900. 

3  Ritter  von  Loessl,   "Die  Luftwiderstanagesetze." 

4  De  Louvrie,  Ch.,  Proc.  Int.  Conference,  1893. 

5  Luyties,  O.  G.,  Aeronautics,  v.  1,  p.  13,  No.  3. 

8  Soreau,   R.,    "Nouvelle   Formule,"   Aerophile,   v.   17,   p.   315. 
7  Langley,   "Experiments  in  Aerodynamics,"  p.  24. 


44 


MONOPLANES  AND  BIPLANES. 


CHAPTER  IV. 

THE  PRESSURE  ON   CURVED  PLANES 

THE  photographs  of  the  stream  lines  about  a  curved  surface  set 
at  a  low  angle  of  inclination  to  the  line  of  flight  bear  full  confirma- 
tion of  its  greater  efficiency.  In  the  photograph  below  is  shown 
the  condition  of  the  air  flow  for  an  arched  or  curved  plane,  almost 
normal  to  the  air  stream,  and  the  regions  of  low  density,  high 
density,  and  discontinuity  appear  similar  to  those  for  a  flat  plane. 
But  when  this  curved  plane  is  inclined  only  slightly  above  the  hori- 
zontal as  shown  in  the  photographs  on  p.  48  and  p.  51,  the  smooth- 


AT  HIGH  ANGLES  OF  INCIDENCE  A  CURVED  PLANE 

CAUSES  AS  GREAT  A  DISTURBANCE  AS  A 

FLAT  ONE 

ness  of  flow  of  the  air  stream  past  the  surface  becomes  strikingly 
evident. 

Langley  it  is  said  investigated  curved  surfaces,  but  his  results 
have  .not  as  yet  been  published. 

Lilienthal,  striving  to  imitate  the  birds,  examined  carefully  the 
shape  and  structure  of  wings  of  the  various  species.1  He  recognized 
the  importance  of  the  shape  of  wing  and  found  after  experiment 
that  even  very  slight  curvatures  of  the  wing  profile  (in  section) 
considerably  increased  the  lifting  power. 

The  arching  of  a  surface  is  the  same  as  its  depth  of  curvature 
and  is  also  sometimes  expressed  as  its  camber  or  cambered  depth. 


46  MONOPLANES  AND  BIPLANES. 

In  the  diagram  below,  if  CB  is  1/12  of  the  chord  AD,  then  the 
surface  shown  in  section  has  a  depth  of  curvature  of  1/12  chord. 

In  a  flat  plane  the  pressure  is  always  perpendicular  to  the  surface 
and  as  pointed  out  above,  the  ratio  of  lift  to  drift  is  therefore  as  the 
cosine  to  j:he  sine  of  the  angle  of  incidence. 

But  in  curved  surfaces  a  very  different  condition  exists.  The 
pressure  is  not  uniformly  normal  to  the  chord  of  the  arc,  but  is 
considerably  inclined  in  front  of  the  perpendicular  at  low  angles 
with  the  result  that  the  lift  is  increased  and  the  drift  is  decreased. 

Lilienthal  was  the  first  to  discover  this  significant  fact  and  fully 
set  it  forth.  He  says:  "When  a  wing  with  an  arched  profile  is 


B 


ACD  *  section 
AD  *  chord 
CB  -  mommum  depth  of  cvn/afvre 

fa>t  necessarily  at  cenTre  c[  section) 

THE  SECTION,  CHORD,  AND  DEPTH  OF  CURVATURE  OF  A  PLANE 
"Depth  of  a  plane"  is  the  same  as  chord. 

struck  by  the  wind  at  an  angle  a  with  a  velocity  V  3  there  will  be 
generated  an  air  pressure  P  which  is  not  normal  to  the  chord,  but 
is  the  resultant  of  a  force  N,  normal  to  the  chord  and  of  another 
force  T  ,  tangential  to  the  chord/' 

These  forces  are  shown  in  the  diagram  on  p.  47.  The  air 
pressure  Pa,  is  precisely  analogous  to  Pa  for  flat  surfaces,  in  that 
it  represents  the  total  effective  force  of  the  air  stream  on  the.  sur- 
face. 

To  determine  N  and  T,  Lilienthal  conducted  a  series  of  experi- 
ments on  planes  shaped  in  plan  somewhat  like  a  bird's  wing  (not 
rectangular).  He  expressed  N  and  T  for  the  surface  he  used,  1/12 
depth  of  curvature,  as  functions  of  P90. 

Thus  N  =  n  X  POO  =  n  X  0.003  8V2 
T  =  t  X  P90  =  t  X  0.003  8V2 


MONOPLANES  AND  BIPLANES. 


47 


where  n  and  t  are  numerical  quantites ;  n  =  1,  when  a  =  90  deg. 
Lilienthal's  results  are  given  in  the  table  on  p.  49. 

Values  of  n  and  t  show  that  arched  surfaces  still  possess  sup- 
porting powers  when  the  angle  of  incidence  becomes  negative.  The 
air  pressure  T  becomes  a  propelling  one  at  angles  exceeding  3  deg. 
up  to  30  deg. 

As  Mr.  Chanute  pointed  out,  this  does  not  mean  that  there  is 
no  horizontal  component  or  "drift"  of  the  normal  pressure  N, 


THE  FORCES  ON  A  CURVED  SURFACE,  IN  AN  AIR  STREAM  V  AT 
AX  ANGLE  OF  INCIDENCE  a 

The  forces  are  assumed  to  be  acting  through  the  center  of  pressure. 


under  these  conditions,  but  that  at  certain  angles  the  tangential 
pressure  T,  which  would  be  parallel  to  the  surface  and  only  produce 
friction  in  the  case  of  a  flat  plane,  acts  on  a  curved  surface  as  a 
propelling  force2. 

Thus  if  it  was  desired  to  find  N  and  T  for  a  surface  100  feet 
square,  moving  at  40  miles  an  hour  and  set  at  an  angle  of  incidence 
of  +  6  degv  the  normal  pressure  P90  would  first  be  computed. 
PW  =  KSV*  =  0.003  X  100  X  1600 
=  480  pounds. 

Then  referring  to  Table  (p.  49)  we  find  that  at  -f-  6  deg.  n  = 
0.696  and  £=  —  0.021. 


48  MONOPLANES  AND  BIPLANES. 

Therefore  N  =  0.696  X  4SD  =  334  pounds 
and  T  =  —  0.021   X  480=— 10.1  pounds. 

Since  its  sign  is  negative  T  is  a  propelling  force. 

The  force  N  is  itself  resolved  into  the  components  L  and  D  as 
was  done  with  Pa  for  a  flat  plane  (see  diagram  p.  47). 

It  is  to  be    observed,  however,  that  T  is  inclined  at  an  angle  a 
above  the  horizontal.     Therefore  to  obtain  its  effect  as  lift  and 


THE  JUSTIFICATION  FOR  THE  USE  OF  CURVED 
SUEFACES 

The  air  streaming  from  right  to  left  past  a 
curved  plane,  showing  the  great  ease  of  flow. 
Compare  with  the  action  on  a  flat  surface. 

drift,  it  must  be  resolved  into  its  vertical  and   horizontal  com- 
ponents.    These  are 

I  =  T  sin.  a 
d=±T  cos.  a 

The  force  I  is  almost  negligible. 
The  total  effective  lift  is  then : 

L'  =  L  +  I  =  (N  cos.  a)  +  (T  sin.  a) 
and  the  total  effective  drift  is: 

D'  =  D  =b  d=  (N  sin  a)    ±    (T  cos  a) 

To  complete  the  numerical  example,  sin  6  deg.  =  0.105  and  cos 
6  deg.  =  0.995.      • 

Then  L'  =  (0.995  X  334)  +  (0.105  X  10.1)  =  333.5  pounds 

D'  =  (0.105  X  334)  —  (0.995  X  10.1)  =  25.0  pounds 
In  this  manner  we  get  the  Lift  and  Drift  of  the  assumed  plane 
at  a  velocity  of  40  miles  an  hour,  according  to  the  Lilienthal  meth- 
od.   The  ratio  of  lift  to  drift  for  this  plane  is  13.3. 

The  experiments  of  Wilbur  and  Orville  Wright  at  Kitty  Hawk 


MONOPLANES  AND  BIPLANES.  49 

verified  the  existence  of  "LilienthaFs  Tangential/'  and  experiments 
conducted  by  them  later  in  the  laboratory  further  supported  this 
fact,  although  their  results  were  smaller  than  those  of  Lilienthal  at 
angles  below  10  deg.3 

LILIENTHAL/S  TABLE,  1/12  CURVE 

t 

—.075 
—.073 
— .07C 
—.065 
—.059 
—.053 
—.047 
—.041 
—.036 
—.031 
—.026 
—.021 
—.016 
—.012 
—.008 
.000 
+.010 
+.016 
+.020 
+.023 
+.026 
+.028 
+.030 
+.015 
15  .901  -.076  90  1.000  .000 

Curve  3  shows  the  variation  of  the  normal  pressure  on  an  in- 
clined plane  according  to  Lilienthal  (curved),  and  the  same  for 
a  flat  plane  according  to  Langley.  The  difference  especially  for 
small  angles,  exhibits  at  once  the  greater  lifting  effect  of  curved 
surfaces. 

In  his  experiments,  it  .appears  that  Lilienthal  did  not  realize 


a 
deg. 

n 

t 

a 
deg. 

n 

—  9 

.000 

+.070 

16 

.909 

—  8 

.040 

+.067 

17 

.915 

7 

.080 

+.064 

18 

.919 

—  6 

.120 

+.060 

19 

.921 

—  5 

.160 

+.055 

20 

.922 

4 

.200 

+.049 

21 

.923 

—  3 

.242 

+.043 

22 

.924 

—  2 

.286 

+.037 

23 

.924 

—  1 

.332 

+.031 

24 

.923 

0 

.381 

+.024 

25 

.922 

+  1 

.434 

+.016 

26 

.920 

+  2 

.489 

+.008 

27 

.918 

+  3 

.546 

.000 

28 

.915 

+  4 

.600 

—.007 

29 

.912 

+  5 

.650 

—.014 

30 

.910 

+  6 

.696 

—.021 

32 

.906 

+  7 

.737 

—.028 

35 

.896 

+  8 

.771 

—.035 

40 

.898 

+  9 

.800 

—.042 

45 

.888 

+10 

.825 

—.050 

50 

.888 

11 

.846 

—.058 

55 

.890 

12 

.864 

—.064 

60 

.900 

13 

.879 

—.070 

70 

.930 

14 

.891 

—.074 

80 

.960 

50 


MONOPLANES  AND  BIPLANES. 


o    ..     b 


MONOPLANES   AND  BIPLANES 


51 


the  full  significance  of  the  movement  of  the  center  of  pressure  or 
point  of  application  of  Pa,  away  from  the  center  of  surface  (see 
p.  64).  Accordingly  his  experimental  values  of  n  and  t  for 
low  angles  are  far  too  great.  For  example,  the  Wrights,  in 
an  experiment  conducted  by  them  on  a  full-sized  aeroplane,  found 
that  Lilienthal's  estimate  of  the  pressure  on  a  curved  surface 
having  an  angle  of  incidence  of  3  deg.  as  equal  to  0.546  of  P90  was 
nearly  50  per  cent  too  great. 

Though  many  excellent  treatises  have  been  written  on  the  sub- 
ject, it  is  hardly  possible  with  the  present  knowledge  of  aerody- 
namics to  explain  exactly  what  the  significance  of  these  pressures 


THE  CONDITION  OF  THE  AIR  STREAM  FLOWING 
BY  A  CURVED  PLANE 

The  dark  region  above  the  plane  indicates 
rarefaction. 

N  and  T  are,  or  to  bring  them  under  any  well-known  set  of  phy- 
sical laws. 

Wegner  von  Dallwitz,  however,  has  succeeded  in  arriving  at  a 
mathematical  expression  of  the  lift  of  a  curved  plane  as 

L  =  K  cos  a  tan2aS.V2 

where  K  is  a  constant  equal  to  0.26  when  metric  units  are  em- 
ployed. 

The  well-known  theory  of  Soreau,  in  which  a  number  of  other 
constants  than  K  are  used,  also  gives  fairly  good  results  by  analyti- 
cal methods. 

THE   RATIO   OF    LIFT   TO   DRIFT 

The  ratio  of  Lift  to  Drift  is,  as  we  have  seen,  of  great  import- 
ance in  the  design  of  aeroplanes,  and  that  surface  which  has  the 


52  MONOPLANES   AND   BIPLANES 

greatest  ratio  of  lift  to  drift,  under  working  conditions,  will  be  the 
most  efficient  from  an  aerodynamic  standpoint,  i.  e.,  it  carries  the 
greatest  weight  with  the  least  power. 

Curve  4  shows  the  variation  of  this  ratio  with  the  incident 
angle  for  both  Langley's  flat  plane  and  Lilienthal's  arched  one. 

The  difference  is  very  pronounced,  and  the  large  values  of  the 
ratio  for  small  angles  show  arched  surfaces  to  be  the  most  economi- 
cal in  flight,  especially  for  soaring  or  gliding. 

Curve  5  shows  the  variation  of  the  ratio  of  lift  to  drift  for 
various  shaped  surfaces  experimented  with  by  A.  Rateau  in  Paris.4 
These  experiments  were  carried  on  in  a  very  complete  manner, 
and  their  results  are  of  great  practical  importance. 

These  experiments  on  the  relation  of  sustaining  power  to  head 
resistance,  on  various  shaped  planes,  show  that  a  thick  curved  plane 
is  by  far  the  most  stable  but  not  so  very  efficient.  The  Antoinette 
monoplane  is  equipped  with  surfaces  of  this  kind. 

That  a  high  aspect  ratio  is  of  great  consequence  is  shown  very 
clearly  by  a  comparison  of  the  curves  corresponding  to  types  2 
and  3. 

The  variations  of  the  ratio  of  L/D  with  aspect  ratio  and  depth 
of  curvature,  however,  are  taken  up  in  detail  in  Chapter  VII;  es- 
pecial reference  is  made  there  to  the  experiments  of  Prof.  Prandtl 
of  Gottingen  and  M.  Eiffel. 

Bateau's  values  of  L/D  for  his  curved  surface  marked  No.  3 
(see  Curve  No.  5)  are  very  high,  compared  to  the  Prandtl  results 
(see  curves  Nos.  12,  13,  14). 

The  1910  experiments  of  M.  Eiffel  on  curved  surfaces  gave  very 
interesting  results.3  In  the  table  on  p.  54  some  of  his  values 
for  a  curved  surface,  150  millimeters  X  900  millimeters,  and  with 
a  depth  of  curvature  of  2/27  chord,  are  tabulated  in  both  metric 
and  English  units. 

M.  Eiffel  expresses  drift  as  a  constant  Kx  multiplied  by  SV2,  the 
usual  value  of  K  for  P90  being  included  in  the  values  for  Kx. 
The  same  is  done  for  lift.  Obviously  at  90  deg.,  the  value  of  Kx 
equals  the  value  of  K,  00314  (see  Chapter  II). 

Eiffel's  values  for  lift  are  very  high  compared  to  those  of  Prandtl. 


MONOPLANES  AND  BIPLANES 


53 


OrJinates  -  Lift  divided  by  Drtft. 


,  o 

6| — 


oo 


54 


MONOPLANES    AND    BJ PLANES 


TABLE  OF  LIFT  AND  DRIFT  OF  EIFFEL'S  CURVED 

PLANE 

Kx  =  Drift  coef.,  Ky  =  Lift  coef. 


a 
0° 
5° 
10° 
15° 
20° 
30° 
45° 
60° 
75° 
90° 


In  Metric  Measures. 
Kx  Ky 

.033 
.054 
.072 
.076 
.067 
.062 
.051 


.003 
.006 
.009 
.017 
.025 
.034 
.049 
.063 
.073 
.076 


.037 

.020 


In  English  Measures. 

Kx  Ky 

.00137 
.00224 
.00298 
.00314 
.00278 
.00257 
.00212 
.00153 


.00012 
.00025 
.00037 
.00071 
.00104 
.00141 
.00203 
.00266 
.00303 
.00314 


.00083 


Roughly  K  in  metric  measures  -f-  by  24.1  =  K  in  English 
measures. 

As  an  example  of  the  manner  in  which  M.  Eiffel's  results  are 
used,  the  same  plane  already  employed  to  illustrate  the  Lilienthal 
method  is  used  again,  S  =  100  square  feet,  and  V  =  40  miles 
an  hour. 

Hence  S.V2  =  160,000. 

Referring  to  the  Table  on  this  page,  it  is  seen  that  at  6  deg. 
the  lift  and  drift  coefficients  are  approximately  0.0024  and  0.00028, 
respectively. 

Therefore, 

Lift    =  Ky  X  SV2  =  0.0024  X  160,000  =  384.0  pounds 
Drift  =  Kx  X  8V2  =  0.00028  X  160,000  =  44.8     pounds 
values  that  are  considerably  higher  than  those  of  Lilienthal. 

1  Lilienthal,  O.,  "Vogelflug  als  Grundlage  der  Fliegekunst" 
Zeit.  fi'.r  Luft.,  v.  14,  heft  10  ;  Aeron.  Annual,  No.  3,  p.  95. 

2  Chanute,  O.,  "Sailing  Flight,"  Aeron.  Annual,  No.  3  p.  115. 

3  Wright,     W.,     "Some    Aeronautical    Experiments,"     Smith. 
Inst.  Rep.  for  1902,  p. -1-45. 

4  Rateau  "Recherches  Dynamiques,"  Aerophile,  v.  17,  p.  338. 

5  Eiffel,  G.,  Soc.  des  Ing.  Civ.  de  France,  1910;  L'Aerophile, 
Feb.  1,  1910,  p.  63. 


CHAPTER  V. 

THE     FRICTIONAL     RESISTANCE     OF     AIR 

It  is  well  known,  from  the  investigations  of  Froude  and  others, 
that  the  frictional  resistance  of  a  body  in  water  was  great.  By 
analogy  it  would  seem  as  if  the  friction  of  the  air  would  also  be 
considerable.  Many  prominent  experimenters  and  investigators, 
however,  have  stated  that  the  tangential  resistance  of  air  is  negli- 
gible. 

Langley  implicitly  assumed  the  effect  of  friction  at  the  speeds 
he  used,  to  be  negligible,  and  did  not  investigate  the  problem  to 
any  extent.1 

Clerk  Maxwell  conducted  experiments  on  the  viscosity  of  the 
air,  i.  e.,  the  internal  friction  of  the  fluid,  and  gave  the  coefficient 
of  viscosity  of  air  as#  =  0.0001878  (1  +  0.0027  6),  6  and  v  being 
taken  as  defined  in  his  paper.2  By  this  formula  the  actual  tan- 
gential force  on  a  plane  of  one  square  foot  area  moving  horizontally 
at  100  feet  per  second  is  less  than  1/50  of  1  per  cent  of  the 
pressure  on  the  same  plane  when  moved  normally  at  this  speed. 

Maxim,  Dines,  and  Kress  considered  the  friction  negligible 
throughout  their  experiments.3 

Armengaud  and  Lanchester,  who  have  thoroughly  investigated 
the  subject,  take  the  opposite  view  and  consider  skin  friction  a 
very  appreciable  factor  in  the  resistance  of  an  aeroplane.4 

Lanchester  gives  the  total  friction  on  both  ends  of  a  plane  as 
0.015  of  the  normal  pressure.  Thus  the  frictional  resistance  F  of 
a  flat  plane  200  square  feet  in  area,  moving  at  50  miles  an  hour, 
and  set  at  an  angle  of  20  deg.,  would  be 

F  =  0.015   (0.003  X  200  X  2500)  X  (0.59) 
=  13.27  pounds 

In  1882  Dr.  Pole  investigated  the  skin  frictional  resistance  of 
the  dirigible  balloon  of  M.  Dupuy  de  Lome  and  found  it  to  be 
0.0000477  dlv2  where  d .is  the  diameter,  I  the  length,  and  v  the 
velocity.5  This  gave  a  very  appreciable  value  to  the  frictional 
resistance. 

W.  Odell  in  1903  conducted  experiments  for  the  purpose  of 
determining  the  friction  of  the  air  on  rotating  parts  of  machines 


56  MONOPLANES    AND    BIPLANES 

and  arrived  at  the  conclusion  that  the  energy  dissipated  per  sec- 
ond =  c  ws  v5  where  c  is  a  constant,  w  the  angular  velocity  of  the 
disks  with  which  he  experimented,  and  v  the  radius  of  the  disk.6 
The  friction  was  found  to  be  considerable,  although  the  character 
of  his  experiments  precludes  their  being  applied  directly  to  aero- 
planes. 

Canovetti  found  the  skin  friction  on  surfaces  equal  to  a  constant 
times  the  square  of  the  velocity,  the  constant  taking  the  value 
0.00012  when  the  metric  system  of  units  was  employed.7 

The  most  thorough  experiments  in  this  line  were  conducted  by 
Prof.  Zahm  in  1903.8  The  results  of  his  experiments  showed  con- 
clusively that  the  friction  of  the  air  on  surfaces  was  a  very  con- 
siderable factor,  and  he  expressed  its  general  value  in  the  formula : 

/  =  0.0000158  /°-07  v  1>85 

where  /=  the  frictional  drag  in  pounds  per  square  foot,  Z  =  the 
length  of  the  surface  in  the  direction  of  motion  in  feet,  and  v  =  the 
velocity  of  the  air  past  the  surface  in  miles  per  hour. 

The  friction  was  found  approximately  the  same  for  all  smooth 
surfaces,  but  10  to  15  per  cent  greater  with  extremely  rough  sur- 
faces such  as  coarse  buckram. 

The  table  on  page  58  gives  Zahm's  values  for  /  as  obtained  by 
experiment  and  from  the  above  formula.  The  frictional  drag  for 
any  intermediate  velocity  or  length  of  surface  may  readily  be  found 
by  interpolation. 

The  frictional  resistance  of  a  flat  or  arched  aeroplane  surface 
of  area  £  is  F  =  2  X  f  X  8 

the  factor  2  being  introduced  because  the  value  of  /  refers  to  a 
single  surface  of  a  plane,  while  a  plane  in  free  flight  has,  of 
course,  two  sides  exposed  to  frictional  resistance. 

To  illustrate  the  practical  application  of  these  results  on  air 
friction,  the  actual  frictional  resistance  F  of  a  biplane  consisting 
of  two  surfaces,  30  feet  wide  and  4  feet  deep,  moving  at  60  miles 
an  hour  is  computed,  8  =  240  square  feet.  From  the  table  on 
page  58  the  value  of  /  =  0.0279. 

;.  F  =  2  X  0.0279  X  240 
=  13.4  pounds. 


MONOPLANES   AND   BIPLANES 


Ordinates-fVictional  Resistance   in  Ite.Jaer 


* . 

? 

1 


s 


58 


MONOPLANES    AND   BIPLANES 


! 

Average  friction  in  pounds  per  square  foot. 

a 

V  plane. 

2'  plane. 

4'  plane. 

&'  plane. 

mi.  hr. 

5 

0.000303 

0.000289 

0.000275 

0.000262 

10 

0.00112 

000105 

0  00101 

0.000967 

15 

0.00237 

000226 

0  00215 

000205 

20 

0.00402 

0.00384 

0.00365 

0.00349 

25 

0.00606 

0.00579 

0.00551 

0  00527 

30 

0.00850 

0.00810 

0.00772 

0.00736 

35 

0.01130 

0.0108 

0.0103 

0.0098 

40 

0.0145 

0.0138 

0.0132 

0.0125 

50 

0.0219 

0.0209 

0.0199 

0.0190 

60 

0.0307 

0.0293 

0.0279 

00265 

70 

0.0407 

0.0390 

0.0370 

0.0353 

80 

0.0522 

00500 

0.0474 

0.0452 

90 

0.0650 

0.0621 

0.0590 

0.0563 

100 

0.0792 

0.0755 

0.0719 

0.0685 

SKIN  FRICTION  TABLE  (ZAHM) 

This  value  is  very  much  less  than  what  would  be  obtained  by 
using  Lanchester's  method. 

The  frictional  resistance  of  air  as  determined  by  Zahm  bears 
a  striking  resemblance  to  that  of  water  as  determined  by  Froude.9 
Froude  found  the  friction  to  vary  very  nearly  as  v1'85,  and  a 
comparison  of  the  results  indicates  that  the  resistances  are  pro- 
portional in  some  way  to  the  densities  of  the  two  media. 

If  it  is  true  that  the  air  stream  never  touches  an  aeroplane 
surface  but  only  comes  in  contact  with  the  air  film  surrounding 
it,  then  the  frictional  resistance  would  be  the  same  for  all  rea- 
sonably smooth  surfaces,  but  would  be  higher  for  surfaces  so 
rough  that  the  fibers  themselves  cause  regions  of  discontinuity. 
This  appears  to  be  borne  out  in  the  results  of  the  experiments 
of  Prof.  Zahm. 

Curve  6  shows  the  variation  of  the  skin  friction  on  a  unit  sur- 
face with  speed  as  plotted  from  Prof.  Zahm's  tables. 

It  is  now  generally  accepted  that  skin  friction  is  an  appreciable 


MONOPLANES   AND   BIPLANES  59 

factor    in    the    resistance    of   an    aeroplane,   and   amounts    in   an 
average  sized  machine  to  from  10  to  25  pounds. 

1  Langley,  S.  P.,  "Exp.  in  Aerodynamics,"  p.  9. 

2  Maxwell,  Clerk,  Phil.  Trans.,  v.  157. 

3  Baden-Powell,   Aeronautics    (Brit.),  v.   1,  p.  117. 

4  Lanchester,    F.    W.,    "Aerodynamics"  ;    Armengaud,    "Prob- 
leme  de  1'Aviation." 

5  Pole,  William,  Eel.  Eng.  Mag.,  v.  27,  p.   1,  1882. 

6  Odell,    W.,    "Experiments    on    Air    Friction,"    Engineering 
(London),  January,  1904. 

7  Canovetti,  "Sur  la  Resistance  de  1'Air,"  Paris,  Acad.  ScL, 
v.  144,  p.   1030. 

8Zahm,   A.   F.,   "Atmospheric  Friction,"  Bulletin,  Phil.   Soc. 
of  Wash.,  v.  14,  p.  247. 

9  Froude,  Brit.  Assoc.  Report,  1872. 


60 


MONOPLANES    AND    BIPLANES 


ll^ll 

^*-iz:  §  ,5  Q  >3 


CS 


'8  ^ 


fe 


S         S 


o 

«)  g 


CHAPTER  VI. 

THE    CENTER   OF   PRESSURE   ON    FLAT    AND    CURVED    PLANES 

IN  unsteady  winds  the  center  of  pressure  on  an  aeroplane  moves 
about  greatly,  and  tends,  by  its  variation  in  position,  to  upset  the 
equilibrium,  so  that  the  efforts  of  many  experimenters,  noticeably 
Alexander  Graham  Bell,  have  been  directed  to  the  construction 
of  an  aeroplane  in  which  the  movement  of  the  center  of  pres- 
sure is  made  very  small.  On  a  small  tetrahedral  cell  the  move- 
ment is  very  light,  and  probably  one  of  the  greatest  advantages 
in  the  Bell  "compound  tetrahedral"  structure  is  that  the  resultant 
center  of  pressure  shifts  to  no  greater  extent  than  for  one  cell 
itself.  This  tends  to  give  an  unusual  stability  to  the  entire 
structure. 

Newton  implicitly  assumed  that  when  a  rectangular  plate  was 
moved  through  the  air  at  an  angle  of  inclination  to  the  line  of 
motion,  the  center  of  pressure  and  the  center  of  the  surface  were 
always  coincident.  It  has  long  been  recognized,  however,  that  this 
is  not  the  case,  and  that  the  position  of  the  center  of  Dressure 
varies  with  the  incident  angle. 

Joessel,  in  1869,  was  the  first  to  experimentally  determine  the 
variation  of  position  of  the  center  of  pressure  at  different  angles.1 
His   experiments   were   conducted  on   square   flat   planes  "and  he 
deduced  as  a  result  of  his  experiments  the  formulae: 
C=  (0.2  +  0.3  sin  a)   L 
d=  (0.3  —  0.3  sin  a)  L 

where  C  is  the  distance  of  the  center  of  pressure  from  the  front 
edge  of  the  plane,  a  is  the  angle  of  incidence,  L  is  the  width  from 
front  to  back  of  the  plane,  and  d  is  the  distance  of  the  center  of 
pressure  from  the  center  of  surface.  These  formulae  indicate  that 
the  center  of  pressure  varies  from  0.5  to  0.2  of  the  distance 
from  the  front  to  the  center  of  the  plane. 

In  1875  Kummer  also  conducted  experiments  on  the  position 


02  MONOPLANES    AND    BIPLANES 

of  the  center  of  pressure.2  The  method  of  experiment  adopted 
by  him  consisted  essentially  in  finding  the  angle  of  inclination 
of  the  plane,  corresponding  to  a  series  of  fixed  distances  of  the 
center  of  pressure  from  the  center  of  figure. 

The  experiments  conducted  by  Langley  with  the  "counterpoised 
eccentric  plane"3  were  also  of  this  character.  Both  of  these  sets 
of  experiments  were  on  flat  square  planes,  and  their  general  re- 
sults given  in  the  table  on  this  page  show  how  closely  they  agree. 

POSITION   OF  CENTER  OF  PRESSURE 

Distance  of  c.  p.  from  center  of  plane  as  percentage 
of  side  of  plane. 

Angle  of  plane  with  , * , 

current.  Langley.  Kummer. 

90  deg.  0  0 

78  deg.  .021 

77  deg.  .022 

67.3  deg.  .042 

62  deg.  .044 

55.8  deg.  ,063 

52  deg.  .056 

45  deg.  .083 

41  deg.  .067 

28  deg.  .125  .089 

2L  deg.  .144 

20.5  deg.  .146 

Neither  of  these  experimenters  obtained  values  for  very  low 
angles. 

M.  Rateau,  in  the  aerodynamic  experiments  recently  conducted 
by  him,  investigated  the  variation  of  position  of  the  center  of 
pressure  on  flat  planes.4  His  results  are  shown  graphically  in  Curve 
7,  and  indicate  that  at  0  deg.  and  near  39  deg.  there  are  regions 
of  great  instability. .  The  results  of  Langley  and  Kummer  are 
also  plotted  on  this  curve  for  comparison. 

The  movement  of  the  center  of  pressure  on  curved  surfaces  is 
quite  different  from  that  on  flat  surfaces. 


MONOPLANES   AND   BIPLANES 


63 


I 


J" 

or 


I 

f 


64  MONOPLANES    AND    BIPLANES 

In  deeply  arched  surfaces  the  center  of  pressure  moves  steadily 
forward  from  the  center  of  surface  as  the  inclination  is  turned 
down  from  90  deg.  until  a  certain  point  is  reached,  varying  with 
the  depth  of  curvature.  After  this  point  is  passed  a  curious 
phenomenon  takes  place:  the  center  of  pressure  instead  of  con- 
tinuing to  move  forward  with  decrease '  of  angle,  turns  rather 
abruptly  and  moves  rapidly  to  the  rear.  According  to  Mr.  Wil- 
bur Wright,  this  action  is  due  largely  to  the  pressure  of  the  wind 
acting  also  on  the  upper  side  of  the  arched  surface  at  low  angles. 
The  action,  however,  is  -unmistakable,  and  has  often  been  observed 
in  practice. 

The  experiments  of  M.  Eateau,  already  alluded  to,  also  in- 
cluded an  investigation  of  the  movement  of  the  center  of  pressure 
on  an  arched  surface,  the  results  of  which  are  shown  graphically 
in  Curve  8.  The  reversal  in  movement  is  very  apparent  in  the 
neighborhood  of  15  deg.  and  shows  strikingly  how  different  the 
conditions  of  pressure  on  a  curved  surface  at  low  angles  are  from 
those  on  flat  surfaces.  A  region  of  instability  at  30  deg.,  how- 
ever, seems  also  to  be  present  in  this  curved  surface. 

The  1910  Eiffel  experiments  on  the  curved  surface,  900  milli- 
meters X  150  millimeters,  already  referred  to,  included  a  de- 
termination of  the  movement  of  the  center  of  pressure.  The 
results  are  given  in  graph  No.  1,  on  curve  sheet  No.  9.  A  re- 
versal at  about  15  deg.  is  here  observed,  but  the  backward  move- 
ment is  not  as  pronounced  as  in  the  Eateau  determination. 

On  curve  sheet  No.  9  are  also  given  the  results  of  the  experi- 
ments of  Prof.  Prandtl,5  on  planes  of  different  curvature.  These 
show  that  as  the  depth  of  curvature  is  decreased  the1  reversal 
point  moves  farther  forward,  and  in  addition,  the  reversal  takes 
place  at  a  lower  angle  and  more  suddenly.  The  backward  move- 
ment, however,  is  greatest  for  the  deepest  curved  surface  (1/10). 
The  results  lead  to  the  conclusion  that  because  of  the  greater 
suddenness  of  reversal,  very  slightly  curved  surfaces  are  more 
dangerous  than  highly  arched  ones,  but  it  must  be  borne  in  mind 
that  the  truly  dangerous  condition  of  movement  of  the  center  of 
pressure  would  be  represented  on  the  curve  sheet  by  the  most 


f '•' 

MONOPLANES   AND   BIPLANES 


fea>- 


66  MONOPLANES    AND   BIPLANES 

nearly  horizontal  line.     This  indicates  that  at  angles  of  from  0 
deg.  to  5  deg.  the  1/10  curve  is  the  most  unstable. 

THE    DISTRIBUTION   OF   PRESSURE 

M.  Eiffel  also  investigated  the  distribution  of  pressure  over 
a  curved  plane  set  at  10  deg.  Some  of  his  results  are  shown  in 
the  diagram  on  this  page,  where  3,  2,  1,  0,  —  1,  and  -  -  10,  —  8, 
-4,  etc.,  are  numerical  quantities,  indicating  the  relative  value  of 
the  pressures,  the  distribution  of  which  are  shown  by  the  contour- 
like  lines  on  the  surface.  On  line  3,  for  example,  every  point 
is  at  a  pressure,  three  times  as  great  as  that  of  every  point  on  line  1. 


-4. 


Lpper  Face 


Letxf/ng 


Lower  fixe 


PirecTicn    of  i^of>oo 

THE   DISTRIBUTION  OF  PRESSURE   ON  A 
PLANE  SURFACE   (  EIFFEL) 

The  dotted  lines,  —  1  on  the  under  surface,  indicate  a  negative 
pressure  at  these  points;  and  this  leads  at  once  to  the  conclusion 
that  it  is  advisable  to  "round"  the  ends  of  the  planes,  as  is  done  on 
the  Bleriot,  Wright,  etc. 

The  considerable  negative  pressure  on  the  upper  face  at  the 
front  suggests  possibly  that  in  this  region  there  is  a  pronounced 
Bernouilli  effect. 

'Joessel,  Memorial  du  Genie  Maritime,  1870. 
2Kummer,  Berlin  Akad,  Abhandlungen,   1875,   1876. 
'Langley,   "Experiments  in  Aerodynamics,"  Chapt,  8. 
^Rateau,  A.,  Aerophile,  v.  17,  p.  330,  August,  1909. 
5  Prandtl,  Mitt.  Coettingon  Aerodyn.  Lab.  ;  Zeit.  fur  Flug.  v. 
Motorl.,  1910. 


CHAPTER  VII. 

THE    EFFECT    OF    DEPTH    OF    CURVATURE    AND    ASPECT    RATIO    UPON 
THE   LIFT   AND   DRIFT   OF    CURVED   PLANES 

THERE  has  been  much  discussion  among  those  actively  inter- 
ested in  aviation  about  the  effect  that  varying  the  curvature  of. 
a  plane  or  changing  its  aspect  ratio  has  on  the  lift  and  drift. 
The  experiments  of  Prof.  Prandtl  have  done  much  to  settle  these 
questions,  however,  and  their  results  are  so  forcibly  brought  out 
that  many  of  them  may  well  be  considered  conclusive. 

DEPTH  OF  CURVATURE 

Curve  Nou  10,  page  69,  shows  the  drift  variation  with  angle 
of  incidence,  for  three  surfaces  of  different  curvature,  but  all 
of  the  same  size  and  aspect. 

The  results  show  that  the  drift  resistance  decreases  as  the 
depth  of  curvature  decreases.  In  other  words,  under  the  same 
conditions,  a  natter  plane  has  a  much  less  dynamic  resistance 
than  a  highly  arched  one.  It  is  largely  for  this  reason  that  nat- 
ter planes  are  more  suitable  to  a  racing  machine.  It  must  be 
borne  in  mind,  however,  that  these  experiments  were  conducted 
on  planes  of  circular  curvature,  and  the  conclusions  arrived  at 
are  only  applicable  to  such  planes.  Where  the  section  is  more 
like  that  of  a  bird's  wing,  very  thick  at  the  front,  or  where  the 
greatest  depth  is  within  a  third  of  the  width  (distance  from 
front  to  back  of  a  plane),  from  the  leading  edge,  the  conditions 
are  likely  to  be  quite  different,  especially  at  high  velocities. 

Curve  No.  11,  page  70,  shows  that  the  lift  of  a  plane  increases 
greatly  as  the  curvature  is  made  deeper.  That  a  natter  plane 
lifts  less  than  a  highly  arched,  however,  has  long  been  surmised. 
The  lift  of  the  1/14  plane  appears  greater  at  small  angles  than 
any  of  the  others.  This  may  be  due  to  experimental  errors. 

Curve  No.  12,  page  71,  shows  the  ratio  of  lift  to  drift  for 
planes  of  varying  curvature,  and  it  may  be  concluded  from  it 


68  MONOPLANES    AND    BIPLANES 

that  the  ratio  of  L/D  is  greatest  for  the  flattest  plane,  1/25  depth. 
The  angle  at  which  L/D  is  greatest  varies  from,  the  neighborhood 
of  4  deg.  for  the  1/25  section,  to  9  deg.  for  the  1/10  section.  There 
is  therefore  additional  reason  for  using  a  nearly  flat  plane  for  a 
high-speed  machine. 

The  author  concludes  from  experiments  of  his  own  that  the 
ideal  section  for  high  speed  is  a  thick  leading  edge,  and  a  nearly  flat 
under  face  with  a  fairly  well  arched  upper  face,  giving  a  consid- 
erable thickness,  about  one-third  back  of  the  leading  edge.  This 
gives  all  the  advantages  of  a  flat  plane  in  reduction  of  drift,  but 
increases  the  efficiency  b}r  reason  of  the  fact  that  a  well 
designed  upper  face  will  so  "influence"  and  guide  the  air  streams 
past  the  surface  that  few  regions  of  discontinuity  will  exist.  The 
thickness,  however,  must  not  be  made  too  great  because  of  the 
higher  resistance  caused  thereby.  The  curved  upper  face  will 
generate  the  well  marked  upward  trend  of  the  advancing  current 
of  air,  a  highly  advantageous  characteristic  of  curved  surfaces 
that  is  very  pronounced  in  all  stream  line  photographs;  it  is  even 
likely  that  this  upward  trend  has  much  to  do  with  the  increased 
lift  of  curved  surfaces  in  that  the  angle  between  the  air  stream 
and  the  chord  of  the  surface  is  much  greater  than  the  angle  of 
incidence,  i.  e.,  between  the  chord  and  the  general  line  of  motion 
of  the  air  stream.  Because  of  this  greater  angle,  the  pressure  on 
the  plane  is  increased,  and  this  increased  pressure  largel}r  turned 
into  lift,  the  drift  remaining  about  the  same,  thus  giving  a  much 
higher  efficiency. 

Eeferring  to  the  stream  line  photograph  on  page  48,  a  region 
of  discontinuity  is  observed  at  the  rear,  trailing  out  from  the 
rear  edge,  and  obviously  due  to  the  sudden  passage  of  the  air 
stream  past  this  sharp  edge.  This  action  certainly  decreases  the 
efficiency  by  increasing  the  resistance.  It  would  appear,  there- 
fore, that  a  gentle  upward  reverse  curvature  of  the  rear  edge 
might  add  to  the  efficiency. 

Not  long  ago  W.  E.  Turnbull  conducted  a  series  of  experi- 
ments on  differently  shaped  sections  of  planes,2  and  found  that 
a  section  of  this  "reverse  curve"  type  gave  excellent  lift  and  a 


MONOPLANES   AND   BIPLANES 


69 


Ordinats  -  Gxf  ef  Drift 

Js &  tx  8  « 


70 


MONOPLANES    AND    BIPLANES 


MONOPLANES   AND   BIPLANES 


71 


72  MONOPLANES    AND    BIPLANES 

very  low  drift.  Incidentally,  he  also  found  that  in  this  kind  of 
a  surface,  the  movement  of  the  center  of  pressure  was  very  regu- 
lar, and  therefore  gave  much  greater  stability.  The  outer  ends 
of  the  v.  Pischof  and  Etrich  monoplanes  (see  Part  II,  Chapter  X) 
are  turned  up,  somewhat  in  this  fashion,  and  it  is  found  that  this 
disposition,  suggested  some  years  ago  by  Tatin,  greatly  adds  to 
the  stability. 

ASPECT  RATIO 

There  is  little  necessity  for  dwelling  at  length  upon  the  ad- 
vantage of  a  high  aspect  ratio,  i.  e.,  the  ratio  of  the  span  of  a 
plane  to  the  depth,  chord,  or  distance  parallel  to  the  direction 
of  the  air  stream.  That  a  broadly  spreading  plane  of  small  chord 
gives  a  much  better  efficiency  than  a  short  span  plane  with  its  long- 
est dimension  from  front  to  rear,  has  long  been  known. 

It  is  interesting,  nevertheless,  to  compare  the  results  of  Eiffel 
and  Prandtl  on  planes  of  different  aspect  ratio  as  is  done  in 
curve  No.  13,  on  page  73. 

Eiffel's  plane  measured  930  millimeters  in  span  and  150  milli- 
meters in  depth,  giving  an  aspect  ratio  of  6  to  1.  PrandtPs  plane 
measured  80  centimeters  in  span  and  20  centimeters  in  depth, 
giving  an  aspect  ratio  of  4  to  1.  The  curvatures  of  the  two 
planes  were  similar.  Yet  the  ratio  of  lift  to  drift  does  not  show 
any  noticeable  difference  except  at  angles  below  4  deg.  At  0  deg. 
there  is  a  very  great  difference,  the  plane  with  the  high  aspect  ratio 
having  a  much  higher  efficiency. 

In  curve  No.  14,  page  77,  are  given  the  results  of  PrandtPs 
experiments  on  planes  of  the  same  curvature  (3/40)  but  of 
different  aspects.  Here  there  is  a  very  distinct  variation,  the 
ratio  of  lift  to  drift  decreasing  greatly  as  the  aspect  ratio  is  de- 
creased. For  the  5.25  to  1  plane,  it  is  nearly  12,  and  for  the 
1  to  1  it  is  4.9. 

The  different  planes  have  their  maximum  values  of  L/D  at 
about  the  same  region,  4  deg.  to  6  deg. 

Comparing  curves  No.  13  and  No.  14,  it  becomes  at  once  evi- 
dent that  Eiffel's  results  for  the  6  to  1,  and  PrandtPs  for  the 
5.25  to  1,  bear  little  resemblance.  PrandtPs  curve,  although  smaller 


MONOPLANES   AND  BIPLANES 


73 


ffclio  ff  L/D 


74  MONOPLANES    AND    BIPLANES 

in  aspect,  having  a  higher  ratio  of  L/D  than  Eiffel's.  The 
results  are  therefore  not  in  good  accord,  and  emphasis  should  he 
laid  on  this  fact  to  show  how  even  at  this  stage,  two  of  the  most 
prominent  experimenters  can  differ  in  their  results.  Excepting 
in  one  or  two  points  such  as  these,  however,  it  must  be  acknowl- 
edged that  the  results  of  Prandtl,  Eiffel,  Eateau,  Spratt?  Lilienthal, 
Langley,  and  others,  do  bear  each  other  out  quite  well. 

Exactly  why  a  high  aspect  ratio  is  so  beneficial  is  not  known, 
but  it  may  possibly  arise  from  two  causes.  First,  there  must  be 
a  leakage  of  air  around  the  lateral  edges  of  a  plane,  and  naturally 
the  smaller  these  edges  the  less  the  leakage.  A  long  plane  with 
a  small  span  would  permit  of  a  much  greater  flow  of  air  out  past 
its  sides  than  along  under  it  and  out  at  the  rear;  while  a  very 
broad  plane  with  a  small  depth  would  have  the  air  stream  largely 
pass  under  it  and  out  to  the  rear,  and  little  leakage  past  the  sides. 
This  at  once  suggests  that  a  shape  of  plane  (in  plan,  not  in 
section)  could  be  designed  in  which  all  the  advantages  of  a  high 
aspect  ratio  are  preserved  without  the  excessively  wide  span,  a 
shape  something  like  that  of  the  Paulhan  biplane.  (See  Part 
II,  Chapter  XI,  page  210). 

The  second  advantageous  characteristic  of  a  high  aspect  ratio 
is  not  so  well  defined.  It  is  a  fact  observable  from  the  stream 
line  photographs  that  the  air  stream  passing  under  an  inclined 
plane  is  gradually  deflected  until  it  leaves  the  region  of  the  rear 
edge  practically  tangential  to  the  surface.  But,  obviously,  if  it 
does  leave  tangentially  or  nearly  so,  there  can  be  little  or  no 
lift  in  this  region.  The  plane,  therefore,  is  not  so  efficient,  the 
drift  of  course  being  slightly  decreased  for  this  region  (due  to  the 
lesser  incidence),  but  the  lift  being  decreased  in  very  much 
greater  proportion.  The  ratio  of  this  "dead"  region  to  the  effective 
area  in  front  of  it  would  certainly  be  greater  on  a  plane  of  low 
aspect  ratio  than  on  one  of  high  aspect  ratio. 

1  Prandtl,  Mitt.  Goettingen  Aerodynamischon  Laboratorium  ; 
Zeit.  fur  Flug.  v.  Motorl.,   1910. 

2  Turnbull,  W.  R.,  "Forms  and  Stability  of  Aeroplanes,"  Sci. 
AM.   SLIPP.,  v.   67,  p.  68. 


CHAPTER  VIII. 

NUMERICAL  EXAMPLE  OF  THE  DESIGN  OF  AN  AEROPLANE 

To  ILLUSTRATE  numerically  the  application  of  the  theoretical 
matter  and  experimental  data  contained  in  the  preceding  chapters 
of  this  volume,  the  following  example  is  given.  Calculations  in 
this  kind  of  work  need  be  made  only  to  5  or  10  pounds  for  lift, 
and  1  or  2  pounds  for  drift.  Any  refined  calculation  to  hun- 
dredths  or  even  tenths  of  a  pound  has  no  raison  d'etre. 

DESIGN  OF  A  BIPLANE 

Weight,  speed  and  angle  of  incidence  assumed:  to  find  the  area 
and  dimensions  of  the  planes  and  rudders  and  the  motive  power 
necessary. 

Let  W  =  total  weight  (including  operator)  =  1000  pounds. 
Let  the  desired  speed  7  =  45  miles  an  hour,  and  let  the  angle 
of  incidence  be  assumed  provisionally  at  5  deg.  We  must  first 
choose  a  type  of  curvature.  This  being  a  rather  slow  and  heavy 
machine  a  1/12  curve  would  answer  well.  A  convenient  aspect  ratio 
such  as  5%  to  1  must  also  be  chosen,  and  depends  primarily  on  the 
type  of  structure  and  materials  to  be  used. 

Since  the  lift  must  equal  the  weight  W,  we  have,  according  to 
Lilienthal,  for  a  1/12  curve, 

Ll  =  1000  =  [(cos  5  deg.  X  n)  +  (  sin  5  deg.  x  t  )]  X  PM 
and  referring  to  the  Lilienthal  table,  page  49,  and  to  a  table  of 
natural  trigonometric   functions  quite   accurate   enough  to   three 
places  for  this  kind  of  work,  we  get  cos  5  deg.  =  0.996  and  sin 
5  deg.  =  0.087.     Then 

//  =  1000=[    (0.996  X  0.650)  -f  (0.087  X  0.014)    ]    P00 
=  0.648  P90 

1000 

:.  P90  =          — -  =  1550  pounds. 
0.648 


76  MONOPLANES    AND    BIPLANES 

LilienthaPs  values  for  lift,  however,  especially  at  5  deg.,  are 
now  generally  conceded  to  be  too  high  for  reasons  explained  in 
Chapter  IV. 

If  we  used  Eiffel's  results  (see  page  54),  the  values  obtained 
are: 

L  =  Ky  X  SV2 
1000  =  0.00224  X  S  V2 
0.00224 

whence  L  =  -      0.00314  SV2 

0.00314 

and  1000  =  0.71  P90,  giving 

1000 

P90  = =  1410  pounds. 

0.71 


AT  BELMONT   PARK.   OCT..   1910 
A  Farman  biplane  closely  followed  by  a  Blcrlot  monoplane. 

But  in  this  case,  it  must  be  borne  in  mind  that  the  aspect 
ratio  is  6  to  1  and  the  curvature  1/13.5,  both  leading  to  a  high 
lift,  so  that  the  value  0.71  is  very  likely  10  to  15  per  cent  too 
high. 


MONOPLANES  AND  BIPLANES 


ffafio  ofL/0 


78  MONOPLANES    AND    BIPLANES 

In  Curve  No.  ID  are  plotted  the  values  of  drift  for  a  plane  with 
a  1/14  depth  of  curvature.  Although  the  aspect  ratio  is  4  to  1 
for  this  surface,  the  effect  of  an  increase  of  aspect  ratio  to  a  higher 
value  would  not  appreciably  alter  the  drift;  it  would  only  increase 
the  lift.  In  Curve  No.  14  are  plotted  the  values  of  Lift/Drift 
for  a  plane  having  an  aspect  ratio  of  5.25  to  1  and  a  curvature 
of  very  nearly  1/12.  For  5  deg.,  L/D  from  Curve  No.  14  equals 
about  12,  and  from  Curve  No.  10,  it  is  seen  that  the  drift  coef. 
equals  .04.  Therefore  the  lift  coefficient  upon  combining  equals 
12  X  0.04  =  0.48. 

Then  L  =  1000  =  0.48  P90 

1000 
and  P90  =     -  =  2080  pounds. 

0.48 

Since  P90  =  KSV2  =  0.003    S  X  2025 

P90  =  6.075  8  or  S  =  P90/6.075 

which  gives  8  =  256  square  feet  by  Lilienthal;  S  =  232  square 
feet  by  Eiffel  and  S  =  345  square  feet  by  Prandtl. 

The  values  of  both  Lilienthal  and  Eiffel  are  certainly  very  low, 
and  to  be  on  the  safe  side,  we  will  use  the  more  reliable  results 
of  Prandtl. 

We  may  therefore  say  that  the  required  area  is  350  square  feet. 

This  is  the  area  necessary  to  give  the  lift  of  1,000  pounds  at  5 
deg.  and  at  45  miles  an  hour. 

The  aspect  ratio  is  to  be  in  the  neighborhood  of  5y2  to  1. 

It  has  already  been  said  that  "rounding"  the  ends  of  planes  is  a 
very  good  practice.  To  do  this  we  must  take  off  about  10  square 
feet  on  each  end  of  the  otherwise  rectangular  planes.  This  means 
that  our  rectangular  dimensions  must  give  40  square  feet  greater 
area,  or  390  square  feet.  Each  plane  then  should  have  the  super- 
ficial dimensions  of  a  rectangle  195  square  feet  in  area. 

The  conditions  are  entirely  satisfied  by  a  biplane,  the  surfaces 
of  which  are  rounded  at  the  ends,  32  feet  6  inches  in  spread  (maxi- 
mum width  side  to  side),  and  6  feet  0  inches  in  chord  (maxi- 
mum distance  front  to  back),  giving  an  aspect  ratio  of  5.42  to  1. 


MONOPLANES   AND   BIPLANES 


This  is  a  provisional  set  of  values  for  the  surfaces.  If 
the  aspect  ratio  or  depth  of  curvature  is  to  be  changed,  the  cor- 
responding changes  in  the  constants  will  give  a  different  P90  and 
a  different  surface,  the  choice  of  values,  as  in  all  kinds  of  en- 


A  GLIMPSE  OF  BLfinioT  SHORTLY  AFTER  FIis  START  ox  His 

HISTORICAL  CROSSING  OF  THE  ENGLISH  CHANNEL, 

JULY  25TH.  1909 


gineering  practice,  depending  in  great  measure  upon  the  experi- 
ence, judgment  and  technical  training  of  the  designer. 

P00  and  the  dimensions  of  the  surface  being  known,  the  drift 
can  now  be  calculated. 


80  MONOPLANES    AND    BIPLANES 

By  Lilienthal.  (see  Table  p.  49). 

"D  =  [  (n  sin  5  deg.)  —  (t  cos  5  deg.)  ]  X  -P90 
=  [  (0.650  X  0.087)  --  (0.014  X  0.996)  ]  X  0.003  X  8  X  Vs 
=  0.042  X  0.003  X  350  X  2025 
=  90  pounds. 

Lilienthal's  values  for  drift  are  generally  thought  to  be  quite 
good. 

Using  Eiffel's  table  (see  p.  54)  Kx  =  0.00025,  and 
D  =  0.00025  SV2 

=  0.00025  X  350  X  2025 
=  177  pounds, 

a  value  that  is  perhaps  a  little  excessive. 
By  PrandtPs  results  (see  p.  69) 
D  =  0.04  X  ESV2 

=  0.04  X  0.003  X  350  X  2025 
=85   pounds 
a  value  that  is  low. 

Lilienthal's  value  of  the  drift  is  quite  reasonable;  allowing  a 
large  enough  factor  of  safety,  we  can  call  the  drift  150  pounds. 

This  150  pounds  is  the  drift  or  aerodynamic  resistance.     To  get 

the  necessary  thrust  of  the  propeller,  we  must  add  to  it  the  head 

resistance  of  the  body  and  framing  H  and  the  frictional  resistance 

F.     Then,  if  we  let  R  =  the  total  resistance  to  motion,  obviously 

7?  =  D  +  H  +  F. 

=  D  +  K  8    V*  +  2fS 

To  get  the  head  resistance,  the  cross  section  of  the  machine  must 
be  reduced  to  an  equivalent  flat  surface.  It  is  unnecessary  to  go 
into  the  detail  of  this  somewhat  laborious  computation,  but  it  con- 
sists in  estimating  with  a  reasonable  degree  of  accuracy : 

1.  The  combined  cross-section  of  wires,  struts  and  framing,  all 
projected  on  a  vertical  plane,  perpendicular  to  the  line  of  flight. 
The  simplest  way  of  obtaining  this  is  to  determine  the  cross-sec- 
tion per  inch  or  per  foot  of  the  wires  allowing  1/16  inch  to  % 
inch  for  vibration,  and  multiplying  by  the  number  of  inches  or 
feet  of  wire  or  cable.  The  same  is  done  for  the  frame  members 
and  the  cross  spars. 


MONOPLANES   AND  BIPLANES  81 

2.     The  projected  area  of  operator  motor  tanks,  seat,  etc. 
All  these  are  added  together,  and  if  we  let  this  area  be  A,  then 
//  =  K  A  V- 

=  0.003  X  A  X  2025 

In  a  machine  of  this  size  A  is  about  3  to  4  square  feet  at  the 
most. 

Then  //  =  0.003  X  4  X  2025 

=  24.3  pounds. 

The  frictional  coefficient  /  is  obtained  by  interpolation  from  the 
Table  on  p.  58,  for  V  =  45  and  a  6-foot  plane. 

/  =  0.0162 
Then  the  frictional  resistance 

F=2  X  0.0162  X  390 

=  12.6  pounds 

The  resistance  of  the  main  biplane  cell  alone  is  then: 
R  =  150  -f  25  +  13 

=  188  pounds. 

But  we  have  not  yet  considered  the  rudders  or  keels,  and  their 
resistance  is  quite  large.  Their  size  in  general  is  dependent  upon 
their  distance  from  the  centers  of  gravity  and  pressure.  If  they 
are  very  far  to  the  rear  as  in  the  Antoinette,  then  their  size  need 
be  much  less  than  if  they  were  placed  near  the  center  of  pressure. 
Their  shape  is  largely  a  matter  of  personal  taste.  In  any  case, 
however,  the  governing  principle  in  their  design,  is  that  they  should 
never  be  so  small,  that  in  order  to  correct  a  very  bad  cant  of  the 
machine,  they  must  be  inclined  at  an  angle  as  high  as  25  deg.  to 
30  deg.  The  pressures  at  such  angles  especially  on  curved  surfaces 
are  unreliable,  and  likely  to  give  only  a  drag,  instead  of  a  righting 
force. 

RUDDER  DESIGN 

A  very  simple  and  efficient  method  of  elevation  rudder  design 
is  to  determine  approximately,  as  we  can  do  from  Prof.  Prandtl's 
results,  what  the  maximum  movement  of  the  center  of  pressure  is 
from  the  normal  position  that  it  is  supposed  to  occupy  at  5  deg. 
and  over,  which -the  center  of  gravity  is  located. 


82  MONOPLANES    AND   BIPLANES 

In  the  diagram  on  this  page,  let  AB  =  the  main  plane,  C  = 
the  normal  position  of  the  center  of  pressure  (and  also  the  center 
of  gravity),  and  CO1  =  the  maximum  backward  movement  of  the 
center  of  pressure. 


Ptnecfion  ef  faavv/ 


DIAGRAM  SHOWING  THE  FORCES  ON  AN  AEROPLANE  SURFACE 

AB  AND  REAR  ELEVATION  RUDDER  ER  WHEN  THE 

CENTER  OF  PRESSURE  MOVES  FROM  C  TO  C1 

Let  ER  be  the  normal  position  of  the  elevation  rudder  (placed 
at  the  rear  as  on  the  Wright,  etc.),  and  ER'  ER" ,  its  maximum 
movement  for  ascent  and  descent  respectively.  The  worst  move- 
ment of  the  center  of  pressure  is  the  backward  one  at  low  angles. 
Assuming  that  C'  represents  the  position  for  0  deg.,  an  inclina- 
tion that  no  operator  is  likely  to  permit  in  ordinary  flight,  although 
he  may  greatly  exceed  it  if  he  desires  to  gain  speed  by  a  sudden 
dive. 

Since  the  center  of  gravity  remains  at  Cf  it  being  assumed 
that  the  elevator  is  normally  non-lifting,  and  that  no  lifting  keels 
are  provided,  the  weight  of  the  entire  machine  will  act  through  C, 
in  the  direction  indicated.  (7',  however,  is  now  the  center  of  sup- 
port, so  that  we  will  have  a  moment  about  0',  equal  to  IF  X  the 
vertical  distance  between  the  action  line  of  W  and  C1 ,  tending  to 
rotate  the  system  in  a  counter  clockwise  direction,  i.  e.,  the  machine 
will  tend  to  plunge.  Incidentally  the  more  sudden  the  movement 
of  the  center  of  pressure  from  C  to  C',  the  more  dangerous  will  be 
this  plunge,  and  there  is  great  possibility  that  a  sudden  movement 
of  this  kind  due  to  a  quick  change  in  the  direction  of  a  gusty  head 
wind,  has  caused  several  of  the  recent,  accidents. 


3IOXOPLANES   AXD  BIPLANES 


83 


To  correct  this  tendency  to  dive,  we  must  make  the  elevation 
rudder  of  such  size  that  when  turned  up  to  position  ER',  the  pres- 
sure on  it  shown  as  PY  X  the  vertical  distance  FC',  will  give  a 
moment  tending  to  rotate  the  system  clockwise,  and  not  only  equal 
to,  but  a  little  greater  than  the  moment  of  W  due  to  its  lever  arm 
about  (7.  Obviously  the  farther  back  we  place  ER,  the  greater  is 


life  181 


COUNT  DE  LAMBERT  CIRCLING  THE  EIFFEL  TOWER  IN  His 

FLIGHT  OVER  PARIS  ON  OCT.  19TH,  1009.     HE 

USED  A  WRIGHT  BIPLANE 

its  lever  arm,  and  consequently  for  the  same  desired  righting 
moment,  the  less  need  be  the  value  of  Py  (i.  e.,  the  smaller  the  sur- 
face necessary).  The  reason  why  ER  should  never  be  turned  at 


84  MONOPLANES   AND   BIPLANES 

too  great  an  angle,  is  easily  shown.  If  it  is  turned  to  the  position 
EV,  then  there  is  acting  on  it  the  normal  force  P90.  The  action 
line  of  this  force  is  m  n,  and  its  value  not  very  much  greater  than 
Py.  But  its  lever  arm  about  C'  is  nC' ,  and  gives  so  small  a  clock- 
wise moment  that  the  rudder  is  practically  ineffective. 

This  same  analytical  method  is  applicable  to  the  determination 
of  the  conditions  for  the  correction  of  the  maximum  forward  move- 
ment of  the  center  of  pressure,  causing  the  aeroplane  to  tip  up 
and  necessitating  a  movement  of  the  rudder  to  ER".  It  may  also 
in  a  measure  be  extended  to  determine  the  size  of  direction  rudders 
and  of  lifting  keels. 

Eeturning  to  our  example,  and  referring  to  curve  No.  9, 
p.  65,  it  is  seen  that  the  position  of  the  center  of  pressure  for 
a  surface  of  this  kind  is  about  44  per  cent  of  the  chord  of  the 
plane  at  5  deg.  from  the  front  edge.  This,  then,  is  to  be  the  position 
of  the  center  of  gravity.  At  0  deg.  it  is  seen  that  the  center  of 
pressure  has  moved  back  to  a  point  70  per  cent  of  the  chord  from 
the  front  edge.  Since  the  chord  is  6  feet,  the  center  of  gravity  is 
to  be  0.44  X  6  =  2  feet  8  inches  from  the  front  edge,  and  of 
course  at  the  center  of  the  machine  transversely.  The  movement 
of  the  center  of  pressure  is  to  a  point  0.70  X  6  or  about  4  feet  2 
inches  from  the  front  edge  of  the  plane.  The  lever  arm  of  the 
force  W  (see  diagram  p.  82)  is  then  1  foot  6  inches. 

The  weight   is   1,000   pounds,   therefore   the  counter  clockwise 
moment  tending  to  cause  the  machine  to  plunge  is: 
M  =  1000  X  1.5 

=  1500  foot-pounds. 

To  determine  the  size  of  rudder  necessary,  let  us  assume  the 
type  of  structure  we  use,  the  strength  of  the  material,  and  the 
weight  we  are  limited  to,  permits  of  carrying  the  rudder  frame- 
work far  enough  to  the  rear  to  make  the  distance  between  the  cen- 
ter of  ER  and  C'  about  30  feet. 

The  maximum  inclination  of  ER'  above  ER,  is  chosen  at  15  deg. 
a  reasonable  limit. 

Then  the  lever  arm  C'F  is  approximately  C'F  =  3Q  feet  X  cos 
15  deg. 


MONOPLANES  AXD  BIPLANES  85 

=  30    X   0.966 
==  28.8  feet. 

The  moment  desired  is  to  be  in  excess  of  1,500  foot-pounds,  and 
is  taken  at  1,600  foot-pounds. 

M'  =  1600  =  28.8  X  Py 
Whence 

py  =  1600/28.8  =  56  pounds. 

Assuming  that  this  rudder  is  a  flat  plane,  curve  No.  2  p.  39  shows 
that  when  a  =  15  deg.,  Pa/P90  =  0.46. 
Then, 

P90  =  Pa/0.46  =  56/0.46  =  122  pounds. 
The  size  of  surface  can  now  be  obtained. 
Since  P90  ==  KSV2 

S  =  P90/KV*  =  122/0.003  X  2025 
=  122/6.075  =  20  square  feet. 

A  very  good  shape  of  rudder  therefore  is  a  plane  10  feet  spread 
and  2.5  feet  depth,  rounded  at  the  corners. 

If  the  aeroplane  is  to  be  used  for  speed  only,  this  size  could  be 
slightly  reduced.    If  it  is  to  be  used  for  fancy  volplanes  and  spirals, 
it  would  certainly  be  wise  to  increase  its  size. 
The  dynamic  resistance  of  this  rudder  is, 
Dy  =  Py  sin  15  deg. 
=  56  X  0.259  =  14.5  pounds. 

MOTIVE  POWEK,  ETC. 

The  extra  resistance  of  the  direction  rudder,  etc.,  may  be  taken 
roughly  at  15  pounds.    Then  the  total  resistance  is  equal  to: 
R1  =  D  +  H  +  F  +  Dy  +  15 

=  (150)  +  (25)  +  (13)  +  (14.5)  +  (15) 
=  217.5  pounds. 

This  is  the  actual  active  thrust  of  the  propeller,  T,  necessary  to 
keep  the  machine  in  flight,  if  all  these  resistances  acted  at  once, 
a  condition  that  is  possible. 

The  power  required  is  the  force  X  the  distance  moved  per  unit 
time. 

Power  ==  T  X  V  =  220  V 


86  MONOPLANES    AND    BIPLANES 

expressed  in  foot-pounds  per  minute,  when  T  the  thrust  is  given 
in  pounds,  and  V  in  feet  per  minute. 

V  =  45  miles  per  hour 
=  3960  feet  per  minute 

ft.  Ibs, 
.  • .  Power  =  220  X  3^60  =  871,200  - 

min. 

1  Horse-power  =  33,000  ft.  Ibs./min. 
871,200 

.  • .  Horse-power  = =  26.4  horse-power. 

33,000 

This  is  all  the  power  necessary  in  the  motor  if  the  generation  and 
transmission  of  the  power  were  perfect.     This  is  never  the  case. 
The  propeller  delivers  roughly  only  75  to  80  per  cent  of  the 
power  put  into  it.     The  motor  itself  and  the  transmission  may 
cause  another  5  per  cent  loss.    Therefore,  to  obtain  the  power  of 
the  motor  necessary,  at  its  ordinary  commercial  rating,  we  may 
consider  the  system  70  per  cent  efficient. 
This  gives  the  horse-power  of  motor 

26.4 
=  -         -  =  38  horse-power. 

0.7 

Therefore,  for  this  machine  a  40  horse-power  motor  will  be 
amply  sufficient.  However,  if  great  quickness  and  ease  of  starting 
is  desired,  or  if  the  machine  is  to  be  flown  at  a  high  altitude, 
more  power  will  be  needed. 

In  order  to  design  the  propeller,  we  may  assume  the  r.  p.  m. 
of  the  motor  at  800.  In  propeller  design,  if  it  may  be  called  such, 
practical  experiment  is  infinitely  more  successful  than  volumes  of 
theoretical  calculations.  The  propeller  industry  is  well  advanced, 
and  many  of  the  propeller  manufacturing  concerns  have  finally 
been  enabled  by  experiment  to  construct  propellers  suitable  to 
different  types  of  machines  and  speeds  with  great  success.  It  is 
hardly  necessary  to  go  into  the  shape,  pitch,  or  form  of  the  blades 
here,  as  these  points  are  largely  matters  of  personal  experience, 
and  individual  conditions.  We  may,  however,  obtain  a  rough  idea 


MONOPLANES   AND  BIPLANES 


87 


of  the  diameter  necessary  by  applying  the  Drzewiecki  method,,  one 
of  several  that  works  out  reasonably  well,  and  given  in  full  in  his 
"Des  Helices  Aeriennes"  (1909). 


"THE  HEAVENLY  TWINS  " 

Johnstone    and    Hoxsey   as    they    were   popularly  called  at  Belmont  Park,  Oct. 
1910,  climbing  for  altitude. 

The  two  useful  equations  of  this  elaborate  theory  are: 

V 


and  d  =  m  X  10 

Where  m  is  a  constant  called  the  "modulus/'  V  =  the  velocity 
in  meters  per  second,  n  =  the  revolutions  per  second,  and  d  =  the 


88  MONOPLANES    AND    BIPLANES 

diameter  of  the  propeller  in  meters.     Converting  the  values  we 
already  have  into  their  proper  units,  we  get: 

66 
V  =  —  —  =  £0  meters  per  second. 


=  0.245 


6.28  X   13 
and 

d  =  0.245   X    10  =2.45  meters 
=  2.45  X  3.28  =  8  feet. 

SUMMARY 

In  this  manner  we  arrive  at  the  design  of  a  biplane  with  the 
following  characteristics : 

Supporting  Area  =  350  square  feet. 

Spread  =  32  feet  6  inches. 

Chord  =   6   feet. 

Angle  of  incidence  =  5  deg. 

Depth  of  curvature  =  1/12  chord. 

Weight  =  1000  pounds. 

Elevation  rudder  =  10  feet  by  2  feet  6  inches,  placed  30  feet 
to  rear,  and  non-lifting. 

Motor  =  40  horse-power  800  r.  p.  m. 

Propeller  =  8  feet  in  diameter. 

Aspect  ratio  =  5.42  to  1. 

'Speed  =  45  miles  per  hour. 

Pounds  carried  per  horse-power  =  25. 

Pounds  carried  per  square  foot  of  surface  =  2.86. 

The  details  of  the  controlling  devices,  transverse  control,  shape 
and  position  of  rudders,  propeller,  motor,  operator,  etc.,  and  the 
type  tff  mounting  are  matters  of  personal  choice.  In  Part  IT, 
ihe  different  dispositions  used  on  the  various  successful  machines 


MONOPLANES   AND  BIPLANES  89 

are  given  in  detail.  In  Part  III,  their  advantages  and  disadvan- 
tages are  discussed. 

This  example,  however,  indicates  with  what  a  degree  of  success 
an  aeroplane  may  be  designed,  by  the  use  of  the  most  elementary 
mathematics  combined  with  experimental  values  of  the  pressures 
on  .aeroplane  surfaces. 

In  a  monoplane,  the  process  of  design  would  be  similar  in  every 
respect.  The  monoplane  has,  in  general,  less  head  resistance  than 
the  biplane,  a  modification  which  means  that  for  the  same  power, 
a  greater  speed  can  be  obtained  and  therefore  a  smaller  surface  is 
needed  for  support. 


PART   II. 

DETAILED  DESCRIPTIONS  OF  THE 
NOTABLE  AEROPLANES 


CHAPTER    IX. 

INTRODUCTION 

The  rapid  progress  that  has  been  made  in  the  practical  appli- 
cation of  the  principles  of  Aerodynamics  is  almost  unparalleled 
in  the  history  of  science.  Within  a  year,  the  number  of  men  mak- 
ing extended  nights  has  increased  so  greatly,  that  we  are  warranted 
in  classing  artificial  flight  with  other  established  means  of  locomo- 
tion. 

The  development  of  the  aeroplane  has  been  accompanied  by 
the  improvement  of  the  dirigible  balloon  or  aeronat,  as  techni- 
cally termed;  and  the  advance  of  both  can  undoubtedly  be  traced 
to  the  combination  of  high  power  and  low  weight  offered  by  the 
gasoline  engine. 

In  the  case  of  aeronats,  however,  as  early  as  1884  the  non-rigid 
type  that  we  have  to-day  had  been  practically  developed  in  the 
dirigible  "La  France/'  built  by  Col.  Renard;  and  although  much 
progress  has  been  made,  it  has  been  more  in  the  line  of  actual  con- 
struction than  in  the  development  of  any  new  principles. 

The  successful  aeroplanes  which  have  been  evolved,  although 
similar  in  their  fundamental  characteristics,  have  begun  to  vary 
from  each  other  in  many  important  details  of  size,  arrangement 
and  efficiency  of  parts.  It  seems,  therefore,  that  we  are  at  a  stage 
where  an  examination  of  these  various  types  for  the  purpose  of 
comparison,  and  a  discussion  of  their  distinguishing  features, 
merits,  and  demerits  would  prove  of  value. 

The  order  in  which  the  types  are  taken  up  is  merely  a  con- 
venient alphabetical  one  adopted  here,  and  is  not  based  on  any 
quality  of  the  machines.  The  biplanes  and  the  monoplanes  are 
separated,  as  they  represent  two  distinct  systems. 

Many  other  systems  of  heavier-than-air  machines  have  been 
constructed,  including  several  triplanes  and  some  extremely  inter- 


92  MONOPLANES    AND   BIPLANES 

esting  helicopters  and  ornithopters,  but  as  yet  none  of  these  has 
demonstrated  successful  flying  qualities,  except  the  Roe  triplane. 

For  the  purpose  of  more  clearly  showing  the  variations  in  size 
of  the  different  types,  detailed  and  dimensioned  plans  and  eleva- 
tions of  each  machine  are  given.  Most  of  these  are  drawn  to  the 
same  scale,  thus  establishing  a  direct  graphic  comparison  of  the 
types. 

It  is  to  be  borne  in  mind  that  inasmuch  as  aviators  are  con- 
stantly changing  and  rechanging  the  dimensions  of  their  machines, 
without  recording  such  alterations,  many  of  the  dimensions  given 
here  are  necessarily  approximate.  In  all  cases,  however,  the  most 
recent  and  accurate  data  as  furnished  by  the  large  number  of  ref- 
erences consulted,  as  well  as  by  close  personal  inspection,  have 
been  made  use  of. 

DEFINITIONS 

In  the  science  of  Aviation  it  has  been  necessary  to  use  a  num- 
ber of  new  terms. 

By  "supporting  plane"  is  meant  the  main  lifting  surface  as 
distinguished  from  all  auxiliary  or  stabilizing  surfaces. 

The  term  "direction  rudder"  refers  to  the  movable  vertical 
surface  used  for  steering  to  right  or  left,  while  the  "  elevation 
rudder ' '  is  that  horizontal  surface  which  is  used  for  steering  up 
or  down. 

" Transverse  control"  is  the  device  used  for  the  preservation 
of  lateral  balance  in  wind  gusts,  and  for  artificial  inclination 
when  making  turns. 

"Keels"  are  fixed  surfaces  exerting  neither  lifting  effect  nor 
rudder  action. 

"Spread"  is  the  maximum  horizontal  dimension  perpendicular 
to  the  line  of  flight,  while  "depth"  is  the  dimension  of  the  plane 
parallel  to  the  line  of  flight. 

By  "aspect  ratio,"  is  meant  the  ratio  of  spr'ead  to  depth,  a 
means  of  defining  the  shape  of  surface. 

"Fuselage"  is  a  long  narrow  girder-like  frame,  often  contain- 
ing the  motor  seat,  etc.  It  could  be  called  the  "backbone"  or 
"spine"  of  a  monoplane. 


MONOPLANES   AND  BIPLANES  93 

"Empennage"  is  a  keel  or  fin,  similar  in  character  to  the  tail 
of  an  arrow. 

"Nacelle."  is  a  boat-like  enclosed  body,  containing  the  seat, 
motor,  etc.,  but  it  is  distinguished  from  "fuselage"  in  that  it  plays 
no  part  in  holding  the  rigidity  of  the  structure. 

A  "tractor,"  screw  pulls  a  machine  (as  on  the  Antoinette),, 
while  a  "propeller"  screw  pushes  a  machine  (as  on  the  Wright 
biplane).  The  term  "propeller,"  however,  generally  refers  to  both 
kinds  of  screws. 

A  plane  is  said  to  be  at  a  "dihedral  angle,"  when  both  sides 
are  inclined  upwards  (positive)  or  downwards  (negative)  from 
the  center. 

"Angle  of  Incidence"  is  the  angle  between  the  chord  of  the 
plane  and  the  relative  direction  of  the  air  stream,  (see  Part  I). 
Often  the  term  "incidence,"  alone,  is  used  in  reference  to  this 
angle. 

"Fusiform,"  "stream-line  form,"  "spindle-shaped,"  are  terms 
descriptive  of  the  torpedo-like  shape  of  a  body  that  gives  small 
resistance. 

The  "Mounting,"  or  "chassis,"  is  the  apparatus  or  framework 
upon  which  the  aeroplane  rests,  starts,  and  alights. 

"Camber"   is  the  rise  in  the  arching   of  a  curved  plane    (see 
p.  46). 

"Chord"  is  identical  with  "depth." 

"Ailerons,"  or  "wing-tips"  are  small  auxiliary  planes  used  to 
preserve  the  side-to-side  balance  of  an  aeroplane. 

"Loading "  is  a  factor  indicating  the  load  in  pounds  that  is 
carried  per  square  foot  of  supporting  surface. 


MONOPLANES   AND   BIPLANES 


MONOPLANES  AT  REST  AND  IN  FLIGHT 


CHAPTEE  X. 

IMPORTANT    TYPES    OF    MONOPLANES 

Monoplanes  exhibit  almost  as  great  a  variety  of  forms  as  bi- 
planes, and  by  actual  statistics  it  appears  that  the  number  of  mono- 
planes flying,  is  far  greater  than  the  number  of  biplanes,  especially 
in  France.  This  is  very  likely  due  to  their  greater  cheapness  and 
simplicity  of  structure  and  the  higher  speed  generally  attainable. 

As  in  biplanes,  there  are  many  prominent  types  that  bear  such 
close  resemblance  to  types  described  here,  that  they  need  not  be 
separately  considered.  The  Albatross  monoplane  is  a  duplicate  of 
the  Antoinette  with  the  exception  that  it  is  fitted  with  a  Gnome 
motor.  The  Deperdussin  and  Eegy  recall  the  Hanriot,  while  the 
Minima  and  Montgolfier  are  similar  in  size  and  aspect  to  the  San- 
tos-Dumont.  The  Humber,  Avis  and  Morane-Saulnier,  all  more  or 
less  resemble  the  Bleriot,  and  the  Vollmoeller  is  very  much  like  the 
Tellier. 

The  eighteen  types  of  monoplanes  described  in  the  following  par- 
agraphs are : 

1.  Antoinette 

2.  Bleriot  XL 

3.  Bleriot  XL   2bis 

4.  Bleriot  XII. 

5.  Bleriot  "Aero-bus" 

6.  Dorner 

7.  Etrich 

8.  Grade 

9.  Hanriot 

10.  Nieuport 

11.  Pfitzner 

12.  Pischof 

13.  E.  E.  P.  (1909) 


96 


MONOPLANES    AND    B1PLAXKS 


14.  E.  E.  P.  (1911) 

15.  Santos-Dumont 

16.  Sommer 

17.  Tellier 

18.  Valkyrie 


THE  ANTOINETTE  MONOPLANE  PASSING  A  WRIGHT  AND  A  VOISIN 

The  propeller  may  be  seen  whirling  at  the  front.     The  bird-like   appearance  is 

striking. 


1.       THE  ANTOINETTE  MONOPLANE 

M.  Levavasseur,  designer  of  the  Antoinette  motor  boats,  is 
credited  with  the  design  of  this  type.  After  building  some  ex- 
perimental machines,  notably  the  Gastambide-Mengin  monoplane, 


UNIVERSITY 

OF 


MONOPLANES   AND  BIPLANES 


97 


the  "Antoinette  IV."  was  built  for  M.  Latham.  This  machine  was 
controlled  transversely  by  means  of  wing  tips,  while  at  present  the 
warpable  surface  control  is  used.  The  Antoinette  is  very  large  and 
remarkably  well  built  from  an  engineering  standpoint,  and  has 
been  operated  very  successfully  by  M.  Latham  in  exceptionally 
high  winds.  Messrs.  Kuller,  de  Mumm,  Thomas,  and  Labouchere, 
have  also  flown  monoplanes  of  this  type,  and  several  have  been  pur- 
chased by  the  French  army.  The  Antoinette,  because  of  its  un- 


LATHAM'S  ANTOINETTE  SOARING  ABOVE  THE  TREES  IN  THE 

INTERNATIONAL  CUP  PtACE  AT  BELMONT  PARK, 

OCT.  29TH,  1910 

usual  gracefulness    always  attracts  a  great  deal  of  attention  and 
admiration. 

The  Frame. — A  long  narrow  frame  of  cedar,  aluminum  and 
ash  carries  at  its  front  portion  the  main  plane,  at  the  extreme 
front  end  the  propeller,  and  at  the  rear  the  rudders.  At  the  bow 
the  frame  resembles  the  hull  of  a  motor  boat,  while  at  the  rear  it 
is  built  in  the  form  of  a  triangular  latticed  girder. 


98 


MONOPLANES    AND    BIPLANES 


SIDE  ELEVATION  AND  PLAN  OF  THE  ANTOINETTE 


MONOPLANES   AND  BIPLANES 


99 


FRONT  ELEVATION  OF  THE  ANTOINETTE 


M.  HUBERT  LATHAM  SEATED  ON  THE  ANTOINETTE 
MONOPLANE 

The  left  hand  wheel  seen  here  governs  the  warping  of 
the    planes.      The   wires   leading  from    the    drum   are 
distinctly  visible. 


100 


MONOPLANES    AND    BIPLANES 


The  Supporting  Plane. — The  carrying  plane  consists  of  a  single 
surface  divided  into  two  halves  of  trapezoidal  shape  set  at  a  slight 
dihedral  angle  and  constructed  of  rigid  trussing  nearly  1  foot  thick 
at  the  center,  covered  over  and  under  with  a  smooth,  finely  pum- 
iced silk.  The  plane  is  braced  also  from  a  central  mast. 

The  spread  is  46  feet,  the  average  depth  8.2  feet,  and  the  sur- 
face area  370  square  feet. 

The  Direction  Rudder. — The  direction  rudder  consists  of  two 


\ 


A  100-H.  P.  ANTOINETTE 

Note    the    boat-like    bow,    the    radiator    along    the    sides   of    the    body,    and    the 

searchlight. 

vertical  triangular  surfaces  at  the  rear,  of  10  square  feet  area, 
They  are  moved  jointly  by  means  of  wire  cables  running  from  a 
lever  worked  by  the  aviator's  feet.  When  this  pedal,  which  moves 
in  a  horizontal  plane,  is  turned  to  the  left  the  aeroplane  will  turn 
to  the  right,  although  in  some  cases  the  opposite  disposition  is 
used. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  a  sin- 
gle triangular  horizontal  surface  placed  at  the  extreme  rear,  and  20 
square  feet  in  area.  It  is  governed  by  cables  leading  from  a  wheel 


'•'(*'" 

MONOPLANES   AND   BIPLANES  101 

placed  at  the  aviator's  right  hand.  To  ascend,  the  wheel  is  turned 
up.  This  causes  the  inclination  of  the  elevation  rudder  with  re- 
gard to  the  line  of  flight,  to  be  decreased  and  the  machine,  there- 
fore, rises. 

Transverse  Control. — The  transverse  equilibrium  is  corrected 
by  warping  of  the  outer  ends  of  the  main  plane  very  much  as  in 
the  Wright  machine.  But  the  front  ends  are  movable  and  the  rear 
ends  rigid  throughout  in  the  Antoinette,  while  the  opposite  is  the 
case  in  the  Wright  biplane. 

The  wheel  at  the  aviator's  left  hand,  through  cables  and  a 
sprocket  gear,  placed  at  the  lower  end  of  the  central  mast,  controls 
the  warping.  For  correcting  a  dip  downward  on  the  right  the 
right  end  of  the  wing  is  turned  up,  and  at  the  same  time  the  left 
end  is  turned  down,  thus  restoring  balance. 

The  controlling  apparatus  is  described  fully  in  Chapter  XIII. 

Keels. — At  the  rear,  leading  up  to  the  rudders,  are  tapered 
keels,  both  horizontal  and  vertical,  that  add  greatly  to  the  bird- 
like  appearance  of  the  aeroplane. 

Propulsion. — A  50  horse-power,  8-cylinder  Antoinette  motor, 
placed  at  the  bow,  drives  direct  a  two-bladed  Xormale,  wooden,  pro- 
peller of  7.25  feet  diameter  and  4.3  feet  pitch  at  1,100  revolutions 
per  minute. 

The  Seat  for  the  aviator  is  placed  in  the  frame  back  of  the 
main  plane.  A  seat  for  a  passenger  is  provided  in  front  of  and  a 
little  below  the  aviator's  seat. 

The  Mounting  is  essentially  on  a  large  pair  of  wheels  fitted  to 
a  pneumatic  spring,,  and  placed  at  the  central  mast.  In  addition  a 
single  skid  to  protect  the  propeller  when  landing  is  placed  in  front, 
and  another  is  attached  in  the  rear. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  1,040  to  1,120  pounds;  the  speed  is 
52  miles  per  hour;  22.4  pounds  are  lifted  per  horse-power,  and 
3.03  pounds  per  square  foot  of  supporting  surface.  The  aspect 
ratio  is  5.6  to  1. 

Recent  Alterations. — The  Antoinette  has  been  slightly  altered. 
The  spread  is  now  49.3  feet,  the  area  405  square  feet,  and  the  total 


102 


MONOPLANES    AND    BIPLANES 


weight  from  1,200  to  1,350  pounds.  Twenty-seven  pounds  are 
lifted  per  horse-power  and  3.33  pounds  per  square  foot  of  surface. 
The  aspect  ratio  is  6  to  1.  A  new  100  horse-power  type  is  also 
being  used  for  racing. 

References. — Aerophile,  v.  17,  pp.  7,  488 ;  Flight,  v.  1, 
pp.  662,  681  ;  Aeronautics,  v.  4,  p.  63 ;  Sci.  AMERICAN,  v. 
100,  p.  352 ;  Rev.  de  1'Av.,  v.  4,  p.  27  ;  La  Nature,  v.  37,  pp. 
49,  329 ;  Zeit.  fur  Luftschiff,  v.  13,  p.  890  ;  Encyl.  d'Av.,  v.  1, 
p.  1  ;  La  Vie  Auto.,  v.  9,  p.  729  ;  Flug  Motor  Tech.,  No.  22, 
p.  10  ;  Boll.  Soc.  Aer.  Ital.,  v.  6,  p.  288  ;  Zeit.  Ver.  Deut.  lag., 
v.  53,  p.  1759;  Genie  Civil,  v.  55,  p.  340. 


THE  BLERIOT  XI  w  FLIGHT 

M.  Louis  Blenot,  its  designer  and  pilot,  the  real  "father"  of 
the  monoplane. 


MONOPLANES    AND    BIPLANES  103 

2.      THE  BLERIOT  XI.   MONOPLANE 

In  1906  M.  Louis  Bleriot  constructed  and  operated  the  first 
successful  monoplane  in  the  world.  He  subsequently  built  type 
after  type,  and  finally  in  1908  succeeded  in  making  several  bril- 
liant and  extended  flights  in  his  large  monoplane  "No.  8  Bis." 
Since  then  he  has  become  world-famous  by  his  flight  of  July  25th, 


CHAVEZ  CLIMBING  OUT  OF  His  BLERIOT  XI  Bis. 

This  gives  a  close  view  of  the  central  fuselage.  Just  back  of  and  below  Chavez 
may  be  seen  the  seat,  control  column  and  a  barograph.  Part  of  the  planes 
and  one  blade  of  the  propeller  are  also  visible.  Note  the  rocker  arm  for 
warping  and  wires  leading  to  the  clocJie,  below  the  fuselage. 


104 


MONOPLANES   AND   BIPLANES 


1909,  when  he  crossed  the  English  Channel,  starting  from  Calais, 
and  landing  near  Dover.  This  flight  was  accomplished  in  the  No. 
XL  type  monoplane,  a  small  one-passenger  machine,  which  is  very 
simple,  and  has  become  extremely  popular.  Among  the  noted  avi- 


~ir~^ — ) 


of  /feel 


THE  BLERIOT  XI  (CROSS  CHANNEL  TYPE)  PLAN  AND  ELEVATIONS 

ators  who  have  flown  this  aeroplane  type  are  also  Delagrange,  Le 
Blon,  Aubrun,  Morane,  Leblanc,  de  Lesseps,  Balsan,  and  Guyot. 
Over  300  of  these  machines  have  been  manufactured  and  sold  by 
M.  Bleriot  since  September,  1909. 


• 
MONOPLANES    AND   BIPLANES  105 

The  Frame. — The  frame  consists  essentially  of  a  long  central 
body  upon  which  the  planes  and  rudders  are  attached.  This  cen- 
tral framework  is  very  lightly  but  very  strongly  built  of  wood,  and 
is  cross-braced  with  wires  throughout. 

The  Supporting  Plane. — The  main  plane  is  situated  near  the 
front,  and  divided  into  two  halves,  each  mounted  on  either  side 
of  the  central  frame  by  socket  joints.  The  halves  of  the  plane  are 
easily  detachable  here,  and  when  not  in  use  are  dismounted  and 
placed  in  a  vertical  position  along  the  frame,  thus  occupying  little 
room. 

The  surfaces  consist  of  ribs  covered  both  above  and  below  by 
Continental  rubber  fabric.  Their  curvature  is  more  pronounced 
than  in  most  other  types,  and  a  sharp  front  edge  is  obtained  by 
the  use  of  aluminum  sheeting.  The  two  halves  are  at  a  slight 
dihedral  angle. 

The  dimensions  of  the  plane  are  spread  28.2  feet,  depth  6.5 
feet,  and  surface  area  151  square  feet. 

The  plane  is  braced  above  and  below  by  wires  from  the  cen- 
tral frame. 

Direction  Rudder. — The  direction  rudder  consists  of  a  small 
surface  4.5  square  feet  in  area  placed  at  the  extreme  rear.  Wire 
cables  leading  to  a  foot  lever  controlled  by  the  aviator  govern  the 
movement  of  this  rudder.  For  turning  to  the  right,  for  example, 
the  aviator  turns  this  lever  by  his  feet  to  the  right  or  left,  de- 
pending on  the  disposition  installed. 

The  controlling  apparatus  is  described  fully  in  Chapter  XIII. 

Elevation  Rudder. — The  elevation  rudder  is  divided  into  two 
halves,  one  mounted  at  each  extremity  of  a  fixed  horizontal  keel. 
The  rudder  is  16  square  feet  in  area.  It  is  operated  by  the  front 
and  back  motion  of  a  "bell  crank"  or  cloche,  as  it  is  called.  This 
latter  device  is  a  universally  pivoted  lever,  in  front  of  the  aviator, 
and  in  a  normal  position  is  vertical.  At  the  lower  extremity  is  at- 
tached a  bell-shaped  piece  of  metal,  affording  a  means  of  at- 
tachment for  the  wires,  and  at  the  same  time  covering  them  to  avoid 
their  entanglement  in  the  aviator's  feet,  etc.  To  ascend  the  avia- 
tor pulls  this  lever  toward  him,  and  to  descend  he  pushes  it  away. 


106  MONOPLANES    AND    BIPLANES 

Transverse  Control. — The  lateral  equilibrium  is  controlled  by 
means  of  the  warping  of  the  main  plane.  The  structure  of  this 
plane  enables  it  to  be  warped,  as  in  the  Wright  machine,  but  in 
this  case  about  the  base  of  each  half,  which  is  rigidly  attached  to 
the  frame  by  the  socket  joints.  The  two  halves  are  warped  in- 
versely by  the  side-to-side  motion  of  the  cloche.  If  the  machine 
should  tip  up  on  the  right,  then  the  cloche  is  moved  to  the  right. 
This  increases  the  incidence  of  the  lowered  side  and  at  the  same 


MOISANT    ON     HIS     BLfiRIOT     XI     BIS 

RETURNING  FROM   His   FAMOUS 

STATUE  OF  LIBERTY  FLIGHT, 

BELMONT  PARK,  OCT. 

30TH,  1910 

time  decreases  that  on  the  raised  side,  thus  righting  the  machine. 
The  combination  of  this  side-to-side  motion  of  the  bell-crank,  with 
the  movement  of  the  foot  lever  controlling  the  direction  rudder, 
is  used  in  turning. 

Keels. — To  preserve  the  longitudinal  stability,  a  single  fixed 
horizontal  keel  is  placed  at  the  rear.  Its  area  is  17  square  feet. 

Propulsion. — At  the  front  of  the  central  frame  is  placed  the 
motor,  originally  a  3-cylinder  Anzani,  developing  23  horse-power. 
This  motor  drove  direct  at  1,350  r.p.m.  a  Chauviere  wooden  propel- 
ler, two-bladed,  6.87  feet  in  diameter  and  2.7  feet  pitch.  Several 


MONOPLANES   AXD   BIPLANES 


107 


of  the  more  recent  aeroplanes  of  this  type  have  been  fitted  with 
Gnome  50  horse-power  rotary  engines,  similarly  placed,  and  driv- 
ing 11/2  foot  propellers. 

The  Seat  is  in  the  frame  back  of  the  main  plane. 

The  Mounting  consists  of  two  large  rubber-tired  wheels  at  the 
front,  mounted  on  an  elastic  chassis.  The  springs  are  made  of 
thick  rubber  rope,  and  afford  great  elasticity  and  strength  with 
small  weight.  There  is  also  a  small  wheel  at  the  rear. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  650  to  720  pounds  and  the  speed  was 
at  first  36  miles  per  hour;  when  a  Gnome  motor  is  used  a  speed 


THE   14-CYL.    100-H.    P.   GNOME   MOTOR   OF   CLAUDE   GBAHAME-WHITE'S    BLERIOT 

RACER  WITH  WHICH  HE  WON  THE  GORDON-BENNETT  CUP  RACE  ON 

OCT.   29TH,   1910,   AT   BELMONT   PARK 

of  48  miles  per  hour  is  attained;  14.4  pounds  are  lifted  per  horse- 
power and  4.5  pounds  carried  per  square  foot  of  surface.  The 
aspect  ratio  is  4.35  to  1. 

The  regular  one-passenger  type  of  this  monoplane  has  further 
been  altered  to  the  new  No.  XL  bis.  in  which  the  sectional  curva- 
ture of  the  planes  is  made  very  nearly  flat  on  the  underside.  This 
change  has  been  found  to  decrease  the  dynamic  or  drift  resistance 
of  the  machine  without  seriously  decreasing  the  lift.  The  speed 


108  MONOPLANES    AND    BIPLANES 

has  been  increased  to  about  52  miles  an  hour.    The  spread  is 
feet  and  the  area  160  square  feet. 

There  are  two  new  models  of  this  macnme  which  have  been 
very  successful.  They  are  the  No.  XI.  21) is.  a  two  or  three-passen- 
ger machine,  and  the  No.  XI.  racing  model. 

The  No.  XI.  racing  model  (type  de  course)  is  the  machine 
upon  which  Leblanc  recently  established  the  speed  record  of  the 
world  by  flying  at  almost  69  miles  an  hour,  and  with  which  Gra- 
hame- White  won  the  1910  Gordon-Bennett  Cup  Eace. 

This  machine  has  a  very  short  body,  flat  planes,  and  a  rein- 
forced frame.  The  surface  has  been  reduced  to  129  square  feet, 
and  the  machine  is  equipped  with  one  of  the  new  14-cylinder  100 
horse-power  Gnome  motors.  The  total  weight  is  about  750  pounds. 
Only  7.5  pounds  are  carried  per  horse-power,  and  as  much  as  5.76 
pounds  are  lifted  per  square  foot  of  surface. 

References. — Zeit.  Ver.  Deut.  Ing.,  v.  53,  p.  1574 ;  Aero- 
nautics, v.  5,  p.  118;  Aerophile,  v.  17,  pp.  102,  106,  129,  318, 
488  ;  Encycl.  d'Av.,  v.  1,  pp.  3,  72,  92 ;  Flug.  Motor  Tech., 
N  .  22,  p.  10 ;  No.  23,  p.  7  ;  No.  25,  p.  14  ;  Flight,  v.  1,  p. 
45:J ;  Boll.  Soc.  Aer.  Ital.,  v.  6,  p.  288 ;  Locomocion  Aerea, 
v.  1,  p.  78;  La  Vie  Auto,  v.  9,  p.  729;  La  Nature,  v.  37,  p. 
32*, ;  Sci.  AMERICAN  SUP.,  v.  68,  p.  136 ;  Bracke,  A.,  "Les 
Monoplans  Bleriot";  Glugsport,  No.  24,  p.  685;  Genie  Civil,  v. 
55,  pp.  260,  344. 


3.    BLERIOT  XI.  2  BIS 

This  machine,  better  known  as  the  "type  militaire,"  resembles 
in  detail  the  other  Bleriot  products,  but  differs  greatly  in  size,  in 
the  fact  that  it  is  a  two-seater,  and  in  the  construction  of  the  fan- 
shaped  tail. 

Like  all  the  new  Bleriot  products,  the  dashboard  in  front  of  the 
seats  is  equipped  with  many  of  the  new  devices,  such  as  recording 
barographs,  speed  counters,  inclinators,  folding  map  cases,  speed- 
ometers, gages,  and  even  thermos  bottles,  an  equipment  that  indi- 
cates the  rapid  trend  of  progress  in  aviation  more  forcibly  than 
anything  else. 


MONOPLANES    AND    BIPLANES 


109 


Many  of  the  famous  trips  of  the  past  year  by  Moisant  (Paris  to 
London),  Morane,  Drexel,  and  others,  have  been  made  on  this  type, 

The  Frame. — The  frame  is  exactly  similar  in  character  to  the 
Bleriot  XI.  Us  frame,  excepting  that  it  is  shorter  in  length  and 
built  more  heavily. 

The  Supporting  Plane. — The  plane  is  of  the  regulation 
Bleriot  type,  fairly  well  arched  (about  5  inches).  The  dihedral 
angle  is  very  slight  indeed.  The  halves  are  braced  from  the  central 
fuselage  and  frame,  in  a  slightly  different  manner  than  on  the  XI. 
bis.  The  plane  has  a  spread  of  36  feet,  a  chord  of  7%  feet,  and 
an  area  of  260  square  feet. 


MORANE   WITH  TWO   PASSENGERS    ON    HlS   BLERIOT  XI   2   BIS 

Note  the  framing,  the  fan-tail  and  the  direction  rudder  at  the  rear. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  two 
semicircular  flaps,  trailing  on  the  end  of  the  dovetail-shaped  keel. 
It  is  operated  by  the  cloche  exactly  as  in  the  XI.  bis. 

The  Direction  Rudder. — The  small  oval-shaped  vertical  sur- 
face at  the  rear  is  the  direction  rudder.  It  is  controlled  as  in  other 
Bleriot  types. 

Transverse  Control. — The  transverse  equilibrium  is,  as  usual  in 
this  make,  controlled  by  warping  the  planes  about  their  base. 


110 


MONOPLANES    AND    BIPLANES 


THE  BLEKIOT  XI  2  BIS.     PiAx,  FRONT  ELEVATION  AND  SIDE  ELEVATION 


MONOPLANES    AND    BIPLANES  111 

Tail. — The  curiously  shaped  tail  on  this  machine  gives  it  a  re- 
markable bird-like  appearance.  It  does  not  exert  any  considerable 
lift.  The  shape  of  the  frame  and  tail  on  the  No.  XIV.,  flown  by 
M.  Bleriot  at  Pau  early  in  1911,  is  quite  different  from  the  ordi- 
nary type.  The  frame  itself  narrows  down,  and  gradually  tapers 
into  the  form  of  the  tail.  The  elevation  rudder  in  this  type  is 
made  of  a  single  surface,  and  the  direction  rudder  is  in  two  halves, 
over  and  under  the  tail. 

Propulsion. — A  seven-cylinder  Gnome  motor  drives  a  7l/2-^oot- 
diameter  Regy  propeller. 

The  seats  for  two  are  placed  side  by  side  in  the  frame  between 
the  two  halves  of  the  plane.  In  the  very  latest  Xo.  XIV.  the 
seats  are  placed  farther  forward,  and  the  frame  in  front  built  more 
in  the  form  of  a  wind  shield. 

Mounting. — The  mounting  is  on  the  usual  Bleriot  wheel  chassis 
at  the  front  and  a  smaller  wheel  at  the  rear.  The  newest  Xo. 
XIV.  has  a  skid  at  the  rear. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  in  flight  is  from  850  to  1,050  pounds.  The 
speed  is  approximately  42  miles  an  hour ;  21  pounds  are  lifted  per 
horse-power,  and  4.1  pounds  carried  per  square  foot  of  surface. 
The  aspect  ratio  is  4.7  to  1. 

References. — V.  Quittner  and  A.  Vorreiter,  Zeit.  fur  Flug. 
und  Motorluft.,  November  26th,  1910 ;  Aero,  1910,  November 
2nd,  p.  350 ;  Aircraft,  December,  1910,  p.  362 ;  Flugsport, 
October  19th,  1910 ;  L' Automobile,  No.  338,  1910 ;  Flight, 
1910,  October  22nd,  p.  861  ;  L'Aerophile,  July  15th,  1910, 
p.  317. 

_4.      THE    BLERIOT    XII.    MONOPLANE 

M.  Bleriot  has  also  designed  a  passenger-carrying  type  of  mono- 
plane, the  Xo.  XII.,  which  differs  in  structure  from  the  Xo.  XI. 
A  type  similar  in  form  to  the  Xo.  XII.  is  the  small  Xo.  XIII., 
with  which  M.  Bleriot  attained  high  speed  at  Eheims  in  1909. 

On  June  12th,  1909,  the  first  flight  of  an  aeroplane  carndng 
three  passengers  was  accomplished  by  M.  Bleriot  on  his  large 
Xo.  XII.  The  machine  at  one  time  became  popular,  and  more 
than  ten  aeroplanes  of  this  type  were  flown. 


112 


MONOPLANES    AND   BIPLANES 


THE  BLERIOT  XII.     SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION 


MONOPLANES    AXD    BIPLANES 


113 


The  Frame. — The  long  central  frame  of  wood  braced  in  every 
panel  by  cross  wires  is  very  deep  at  the  front  and  tapers  gracefully 
to  a  point  at  the  rear. 


GRAHAME-WHITE  ON  A  BLERIOT  XII. 
The  regulation  cloche  and  foot-bar  are  clearly  visible. 

The  Supporting  Plane. — On  the  upper  deck  of  the  central 
frame  at  the  front  is  placed  the  main  plane,  which  is  continuous 
and  perfectly  horizontal.  The  plane  is  braced  by  wires  from  the 
frame  and  its  structure  is  similar  to  that  of  the  Bleriot  No.  XI. 
The  spread  is  30.2  feet,  the  depth  is  7.6  feet,  and  the  surface  area 
is  22S  square  feet. 

The  Direction  Rudder. — A  single  surface  placed  at  the  rear 
extremity  of  the  vertical  keel  is  used  as  the  direction  rudder.  Its 
area  is  9  square  feet  and  it  is  operated  by  a  foot  lever  as  in  No. 
XI. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  a 
single  surface,  placed  at  the  extreme  rear  and  20  square  feet  in 
area.  It  is  operated  by  the  front  and  back  motion  of  the  cloche. 

Transverse  Control. — To  preserve  the  lateral  balance  the  main 
surface  is  warped  inversely  by  the  side-to-side  motion  of  the  cloche, 


114 


MQNOPLANES    AND   BIPLANES 


exactly  as  in  No.  XI.    A  small  surface  under  the  seat  also  aids  in 
lateral  balancing. 

Keels. — A  horizontal  keel  of  21  square  feet  area  is  placed  on 
the  framework  at  the  rear,  but  somewhat  in  front  of  the  elevation 
rudder. 


THE  BLERIOT  XII.  IN  FLIGHT. 


Propulsion. — A  60  horse-power  8-cylinder  E.  N.  V.  motor  is 
placed  in  the  frame  under  the  main  plane.  This  motor  drives  by 
a  chain  transmission  a  single  2-bladed  Chauviere  propeller,  the 
axis  of  which  is  placed  on  the  edge  of  the  main  plane.  This  pro- 
peller is  8.8  feet  in  diameter  and  9  feet  pitch,  and  turns  at  600 
r.p.m. 

The  Seat  or  bench  for  three  is  placed  in  the  frame  under  the 
main  plane  and  back  of  the  motor. 

The  Mounting  is  similar  to  that  on  No.   XI. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  1,150  to  1,300  pounds.     The  speed 


MONOPLANES    AND    BIPLANES 


115 


is  48  miles  per  hour;  21  pounds  are  lifted  per  horse-power  and  5.3 
pounds  per  square  foot  of  surface.     The  aspect  ratio  is  4  to  1. 

References. — Aerophile,  v.  17,  pp.  319,  488 ;  Sci.  AMERICAN 
SUP.,  v.  68,  p.  136  ;  Encyl.  d'Av.,  v.  1,  pp.  72,  92  ;  Plug.  Motor 
Tech.,  No.  20,  p.  18 ;  No.  22,  p.  10 ;  La  Vie  Auto,  v.  9,  p.  729 ; 
Locomocion  Aerea,  v.  1,  p.  28;  Aeronautics  (Brit.),  v.  2,  p. 
11 '<  ;  L' Automobile,  v.  7,  p.  520;  Genie  Civil,  v.  55,  p.  344. 

5.       THE  BLERIOT  ^AERO-BUS" 

The  four-seater  Bleriot  "Aero-bus/7  first  flown  in  February, 
1911,  at  Pau,  is  a  very  marked  departure  from  the  usual  Bleriot 
types. 


THE    BLfiEIOT    "AERO-BUS" 

Eight  passengers  at  the  front  and  one  at  the  rear  about  to  start  a  flight. 
Le  Martin,  the  pilot,  has  hold  of  the  cloche. 

The  passengers  sit  under  the  main  plane,  as  on  the  old  No. 
XII,  and  as  many  as  nine  passengers  have  been  carried  with  ease. 


116 


MONOPLANES    AND    BIPLANES 


The  accompanying  photographs  give  an  excellent  idea  of  the 
framing  and  disposition  of  parts.  The  huge  propeller,  10  feet  in 
diameter,  is  driven  by  a  100  horse-power  Gnome  motor  equipment. 

The  front  elevation  rudder  and  ailerons  for  transverse  control 
bear  distinct  resemblance  to  the  Farman  biplanes.  The  practical 


SIDE  VIEW  OF  THE  BL&RIOT  "AERO-BUS' 


REAR  VIEW  OF  THE  BLERIOT  "AERO-BUS" 
The  deep  ribs  are  clearly  shown  in  this  photograph,  as  are  also  the  ailerons. 


MONOPLANES    AND   BIPLANES 


117 


elimination  of  cross-wires  in  the  main  framing  and  bracing  of  the 
planes  on  this  type  is  a  constructional  detail  that  is  worthy  of 
note. 

The  spread  of  this  machine  is  43  feet  and  the  surface  area 
430  square  feet. 


DETAIL  VIEW  OF  THE  BL£RIOT  "AERO-BUS" 

The  propeller,  motor,  and  gasolene  tank  are  grouped  above  and  supported  on 
strong  framework. 

The  weight,  empty,  is  1,323  pounds,  and  the  maximum  "live 
load"  carried  is  about  1,100  pounds;  24.25  pounds  are  lifted  per 
horse-power  and  5.63  pounds  per  square  foot  of  surface. 


THE  DORNER  MONOPLANE 


The  progress  in  Germany  during  1910  was  by  no  means  re- 
stricted to  imitating  the  French,  as  commonly  supposed,  but  on 


118  MONOPLANES    AND   BIPLANES 

the  contrary  many  interesting  and  distinctive  types  of  aeroplanes 
were  evolved.  Among  these  one  of  the  most  successful  is  the  Dor- 
ner  monoplane.  This  type  resembles  the  v.  Pischof  more  than 
any  other.  The  weight  carried  per  horse-power  and  the  speed 
attained  are  high. 


THE  DORNEK  MONOPLANE.     SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION 


MONOPLANES    AXD    BIPLAXES  119 

The  Frame. — A  triangular  frame,  wide  and  deep  at  the  front, 
and  the  lower  main  member  of  which  is  projected  out  forward, 
serving  as  a  skid,  narrows  to  a  point  at  the  rear.  The  frame  has 
not  many  cross  wires,  since  inclined  struts  are  used  for  giving 
the  required  rigidity.  The  entire  length  of  the  machine  is  34 
feet. 

The  Supporting  Plane. — The  main  plane  is  perfectly  horizon- 
tal and  continuous  as  on  the  old  Bleriot  XII.  It  is  rounded  at  the 
ends  and  warpable.  The  spread  is  38  feet,  the  chord  8%  feet,  and 
the  surface  area  280  square  feet.  The  plane  is  braced  from  a 
central  mast. 

The  Elevation  Rudder. — The  dove-like  shaped  tail,  60  square 
feet  in  area,  is  very  flexible  and  is  bent  as  on  the  Grade.  The 
control  is  by  means  of  a  lever  in  the  aviator's  left  hand,  which 
when  pushed  forward  bends  the  tail  down  and  causes  descent  and 
when  pulled  back  causes  ascent. 

The  Direction  Rudder. — A  single  flexible  16  square  foot  surface 
at  the  rear  over  the  horizontal  tail  serves  as  the  direction  rudder. 
It  is  bent  over  to  either  side  by  means  of  a  lever  in  the  aviator's 
right  hand. 

Transverse  Control. — The  main  surface  is  warped  by  the  feet 
acting  on  pedals  as  on  some  of  the  latest  French  biplanes. 

Tail. — The  gracefulness  and  simplicity  of  the  tail  on  the 
Dorner  is  quite  in  contrast  to  the  complicated  structure  on  the 
Pischof,  the  rudders  themselves,,  when  not  in  use,  acting  as  a  sta- 
bilizing empennage. 

Propulsion. — The  radiator,  and  four-cylinder  22  horse-power 
water-cooled  Dorner  motor  are  placed  in  front  of  the  two  seats, 
all  under  the  lower  plane,  as  on  the  Bleriot  XII.  and  Pischof.  The 
motor  drives  by  chain  a  three-bladed  wood  and  metal  Dorner  pro- 
peller, 8.4  feet  diameter  and  6%  feet  pitch,  at  670  r.p.m.  The 
propeller  is  placed  on  a  level  with  the  entering  edge  of  the  main 
plane,  at  the  rear. 

Mounting. — The  mounting  is  mainly  on  two  rubber-tired 
wheels,  and  the  main  central  skid  at  the  front,  with  also  a  small 
skid  at  the  rear. 


120  MONOPLANES    AND    BIPLANES 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  speed  is  50  miles  an  hour.  The  total  weight  is  from  770 
to  940  pounds;  as  much  as  39  pounds  are  carried  per  horse-power, 
and  3  per  square  foot  of  surface.  The  aspect  ratio  is  4.6  to  1. 

References. — Vorreiter,  A.  "Jahrbuch,  1911,"  p.  Ill ;  Zeit. 
fiir  Luftschiff,  No.  2,  1910;  Zeit.  fur  Flug.  u  Motorluft.,  Sep- 
tember 24th,  1910;  L'Aerophile,  December  15th,  1910,  p.  559. 

7.     THE  ETRICH  MONOPLANE 

In  Austria,  the  progress  of  aviation  during  the  past  few  years 
has  been  closely  bound  up  with  the  efforts  of  Igo  Etrich  and  his 
associate,  Herr  Wels.  Many  years  ago  they  began  experimenting 
on  lines  laid  down  by  the  famous  Austrian  pioneer,  Kress,  whose 
work,  more  or  less  contemporaneous  with  Maxim,  Langley,  Eenard, 
and  Lilienthal,  is  well  known.  In  1906  they  experimented  suc- 
cessfully with  a  glider  at  Oberaltstadt,  Bohemia.  After  having 
built  many  experimental  machines  at  a  time  when  motors  were 
the  cause  of  so  much  trouble  to  prospective  aviators,  Etrich  and 
Wels  finally  evolved  a  somewhat  successful  type  of  monoplane  in 
the  early  part  of  1938.  This  machine,  named  by  them  the  "Etrich- 
Wels  III."  was  substantially  the  same  as  the  present-day  type,  ex- 
cepting that  it  was  equipped  with  a  front  elevation  rudder  which 
was  later  discarded. 

During  1910,  along  with  the  progress  elsewhere,  Austria, 
represented  by  the  Etrich  IV.  and  the  Warcholovski  biplane  (also 
designed  by  Etrich),  jumped  to  the  fore.  Illner,  one  of  the  best 
Etrich  monoplane  pilots,  flew  from  Steinfelde  to  Vienna  across 
country  on  May  17,  1910;  made  an  80-kilometer  cross-country 
flight  on  October  6th,  1910;  flew  from  Vienna  to  Horn  and  back, 
a  distance  of  160  kilometers,  four  days  later;  and  in  the  last  week 
of  the  same  month  made  a  magnificent  duration  flight  of  over  two 
hours.  Aman  has  flown  the  Etrich  well  in  France,  and  at  Johan- 
nisthal  (Berlin)  the  new  Etrich-Rumpler  made  an  excellent  show- 
ing. The  career  of  the  Etrich,  in  fact,  has  been  so  brilliant  that 
the  Austrian  Minister  of  War  is  said  to  have  ordered  twenty  of 
this  type  for  the  army. 


MONOPLANES    AND    BIPLANES 


121 


The   Frame. — The   frame   of   this   machine   is   quite   original. 
The  main  bracing  of  the    plane    consists    of    a    single    panel    of 


THE  ETRICH  MONOPLANE.     SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION 


122  MONOPLANES    AND    BIPLANES 

wire  trussing  and  struts,  very  much  as  on  a  biplane,  and  placed 
laterally  under  the  main  plane.  There  is  a  central  fuselage,  and 
central  struts  as  well  as  large  struts  at  the  outer  end  of  each  wing 
from  which  the  plane  is  braced  by  a  great  number  of  wires.  The 
entire  construction  reminds  one  of  the  old  Lilienthal  machines,  and 
is  in  fact  a  distinct  development  of  them,  Etrich  having  the  dis- 
tinction of  possessing  one  of  these  famous  gliders.  It  is  evident 
in  the  frame  work  and  construction  of  the  entire  machine  that  the 
structure  of  a  bird's  wing  has  been  very  carefully  studied,  many 
features  of  the  ribs,  etc.,  resembling  the  feathers  of  a  bird.  Steel 
tubing  and  fine  wood  and  cross-wire  construction  is  used  profusely 
throughout  the  frame. 

The  Supporting  Plane. — The  plane  is  shaped  like  a  bird's 
wing  and  is  tipped  up  at  the  rear  ends,  a  device  for  stability 
that  was  suggested  by  Victor  Tatin  as  well  as  by  Lilienthal  and 
that  is  also  used  on  the  Pischof  monoplane.  The  halves  are  at  a 
small  dihedral  angle  as  well.  The  sectional  curvature  is  of  the 
well-known  Lilienthal  bird-like  form.  The  spread  is  46  feet,  the 
maximum  chord  is  9%  feet,  and  the  area  344  square  feet.  The 
ends  have  a  depth  of  over  12  feet. 

Tlie  Elevation  Rudder. — At  the  rear  is  a  very  bird-like  tail, 
the  trailing  edge  of  the  horizontal  empennage  being  moved  up  or 
down  for  ascent  or  descent.  The  control  is  by  means  of  a  column 
which  is  pivoted  to  move  backward  and  forward,  a  forward  push 
turning  the  tail  down,  etc.  The  rear  horizontal  empennage  and 
tail  is  14  feet  long  by  11  feet  wide. 

The  Direction  Rudder. — Two  triangular  surfaces  are  used,  very 
much  resembling  the  Antoinette.  Kectangular  surfaces  are  also 
sometimes  used.  They  are  operated  by  the  two  foot  pedals.  To 
turn  to  the  right,  for  example,  the  left  pedal  is  pressed  down  and 
the  right  up.  This  turns  the  rudder  and  at  the  same  time  turns 
the  front  wheels  out  to  the  left.  The  opposite  control  has  also  been 
employed  occasionally,  i.  e.,  the  right  pedal  pressed  down  for  a  turn 
to  the  right. 

Transverse  Control. — Warping  of  the  wings  is  used  for  trans- 
verse control ;  the  mechanism  accomplishing  it  consists  of  wire  and 


MONOPLANES    AND    BIPLANES  123 

pulley  connections  to  the  steering  wheel  mounted  on  the  control 
column.  By  turning  the  wheel  clockwise,  the  left  side  is  turned 
down  and  therefore  lifts  up,  while  the  right  is  turned  up  and 
therefore  sinks.  The  entire  rear  edge  of  the  wing  is  flexible. 
The  warping  alone,  however,  is  not  supposed  to  be  entirely  respon- 
sible for  the  lateral  movement.  The  rear  turned-up  ends  are  so 
curved  that  when  warped  up  considerably,  they  form  a  pocket, 
very  much  like  the  blade  of  a  turbine,  which  catches  the  air,  and 
slows  down  that  side.  The  other  side  then  flies  around  and  due 
to  its  higher  speed  and  consequent  increase  of  lift,  cants  up 
greatly.  The  result  is  that  turns  of  such  sharp  curvature  can  be 
made,  that  the  machine  appears  merely  to  pivot  around  the  inside 
wing. 

Tail. — The  bird-like  tail  has  vertical  and  horizontal  empen- 
nages. The  entire  body  is  inclosed  and  shaped  fusiform,  adding 
still  more  to  the  bird-like  appearance. 

Propulsion. — Formerly  a  Clerget  four-cylinder  50  horse-power 
motor,  mounted  at  the  front  as  on  the  Antoinette,  was  used,  but 
of  late  both  Rumpler  eight-cylinder  55  horse-power  and  Austrian 
Daimler  four-cylinder  65  horse-power  motors  have  been  used.  The 
propeller  is  a  Chauviere,  7.2  feet  in  diameter,  4  feet  pitch,  and 
rotates  at  1,400  r.p.m. 

The  Mounting. — The  mounting  chassis  resembles  somewhat  the 
Bleriot.  On  the  newest  machines  a  large  front  skid  has  also  been 
fitted.  There  is  a  small  skid  at  the  rear. 

The  seat  is  placed  about  in  the  center  of  the  main  plane,  and 
is  well  protected  from  the  exhaust,  slip  stream  of  the  propeller,  etc. 
Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  51  miles  an  hour.  The  total  weight  in  flight  is 
1,100  pounds;  20  pounds  are  lifted  per  horse-power,  and  3.2 
pounds  per  square  foot  of  surface.  The  aspect  ratio  is  4.72  to  1. 

References. — F'achzeit.  fur  Flug.,  October  16th,  1910,  p.  15; 
November  13th,  1910,  p.  23 ;  L'Aerophile,  March  1st,  1908, 
p.  80  ;  June  15th,  1910,  p.  271  ;  December  15th,  1910,  p.  559  ; 
Allge.  Auto.  Zeit.,  October  16th,  1910;  Aircraft,  November, 
1910,  p.  325;  Flugsport,  October  5th,  1910,  p.  602;  Plight, 
May  14th,  1910 ;  Aero,  November  30th,  1910,  p.  428  ;  La  Con- 
quete  de  1'Air,  September  15th,  1910. 


12-i  MONOPLANES    AND    BIPLANES 

8.      THE   GKADE   MONOPLANE 

Herr  Grade  has  the  distinction  of  being  one  of  the  first  Ger- 
man aviators  to  design  and  successfully  fly  an  aeroplane.  In  the 
fall  of  1909  he  began  flights  on  his  interesting  monoplane,  and  on 
October  30th,  1909,  won  the  $10,000  Lanz  prize  for  a  German- 
built  machine.  Since  then  Herr  Grade  has  made  many  excellent 
flights,  and  in  the  recent  race  meeting  at  Heliopolis  he  took  a 
notable  part.  His  machine  is  simple  and  flies  easily.  Many  dupli- 
cates of  this  type  have  been  sold.  Among  those  who  have  flown 
this  type  are  Eode,  Treitschke  and  Plochman,  who  was  later  killed 
on  an  Aviatik  biplane. 


THE  GRADE  MONOPLANE  IN  FLIGHT 

The  Frame. — The  frame  consists  essentially  of  a  main  metal 
tube  chassis  at  the  front,  from  which  a  long,  thick  piece,  support- 
ing the  rudders  is  run  out  to  the  rear. 

It  is  remarkable  for  its  simplicity. 

The  Supporting  Plane. — The  main  surface  is  made  of  Metzeler 


MONOPLANES    AND    BIPLANES  125 

rubber  fabric  stretched  over  a  bamboo  frame.  The  surface  is 
very  flexible  and  the  two  ends  are  slightly  turned  up  from  the 
center.  The  curvature  is  almost  the  arc  of  a  circle  and  the  sur- 
face is  very  thin.  The  spread  is  33  feet,  the  depth  8.5  feet,  and 
the  area  270  square  feet. 

The  Direction  Rudder. — The  direction  rudder  consists  of  a 
single  flexible  surface  of  about  16  square  feet  area,  carried  at  the 
rear  and  controlled  by  a  lever  operated  by  the  aviator.  The  sur- 
face is  not  hinged,  but  is  merely  bent  by  the  controlling  wires  in 
the  desired  way. 

The  Elevation  Rudder. — The  elevation  rudder  consists  also  of 
a  single  flexible  surface  placed  at  the  rear.  Its  area  is  about  20 
square  feet  and  it  is  operated  by  a  large  lever  universally  pivoted 
on  the  frame  above  the  aviator.  To  rise,  this  lever  is  pulled  up, 
and  to  descend,  it  is  pushed  down,  thus  respectively  bending  up 
and  bending  down  the  rear  horizontal  surface. 

Transverse  Control. — The  transverse  control  is  effected  by 
warping  the  main  surfaces.  This  is  accomplished  through  wires 
leading  from  the  large  lever  previously  referred  to.  Side  to  side 
motion  of  this  lever  warps  the  surfaces  inversely.  Thus  if  the 
machine  tips  down  on  the  right,  the  lever  is  moved  over  to  the 
left,  thus  raising  the  depressed  side  and  depressing  the  elevated 
side. 

Keels. — The  tapering  ends  of  both  the  direction  and  elevation 
rudders  can  be  considered  as  keels.  An  additional  vertical  keel 
is  placed  in  front,  both  above  and  below  the  main  surface. 

Propulsion. — A  4-cylinder  24  horse-power  V-shaped  motor  is 
placed  at  the  front  edge  of  the  plane.  It  drives  direct  at  1,000 
r.p.m.  a  2-bladed  metal  propeller  6  feet  in  diameter  and  4  feet 
pitch.  A  Chauviere  propeller  has  also  recently  been  fitted. 

The  Seat  is  placed  under  the  plane,  and  consists  of  a  hammock- 
like  piece  of  cloth  which  gives  great  comfort  and  little  weight. 

The  Mounting  is  on  two  wheels  at  the  front  and  one  smaller 
one  at  the  rear.  There  are  no  springs  provided  whatsoever  on  the 
chassis.  The  front  wheels  are  fitted  with  a  rake  to  bring  the 
machine  to  a  stop  shortly  after  landing. 


126 


MONOPLANES    AND    BIPLANES 


Weight,  Speed,  Loading  and  Aspect  Ratio. — 
The  total  weight  is  from  400  to  500  pounds.     The  speed  is 
approximately  52  miles  per  hour;  17  pounds  are  lifted  per  horse- 


THE  GRADE  MONOPLANE.     SIDE  ELEVATION,  PLAN  AND  FRONT  ,ELEVATION 


MONOPLANES    AND    BIPLANES  127 

power  and  2.0  pounds  per  square  foot  of  surface.    The  aspect  ratio 
is  3.9  to  1. 

References, — Sci.  AMERICAN,  v.  101,  p.  292  ;  Aerophile,  v. 
17,  pp.  439,  508 ;  Zeit.  fiir  Luftschiff,  v.  13,  pp.  802,  957 ; 
Aero,  v.  1,  p.  405;  Motor  Car  Jour.,  v.  2,  p.  794;  La  Vie 
Auto,  v.  9,  p.  711 ;  Zeit.  Ver.  Deut.  Ing.,  v.  53,  p.  1762. 

9.      THE  HANRIOT  MONOPLANE 

The  Hanriot  monoplane  is  a  very  recent  type,  with  which  ex- 
cellent results  have  been  obtained.  It  does  not  in  any  way  depart 
radically  from  the  regulation  monoplane  lines,  but  differs  largely 
in  structural  details  and  dimensions.  Vidart,  Wagner,  Marcel 
Hanriot,  and  Deletang,  are  some  of  the  noted  pilots  of  this  ex- 
quisitely graceful  machine. 


CONTROL  LEVER  AND  SEAT  OF  THE  HANRIOT 
A  photograph  of  the  Hanriot  in  flight  is  given  in  the  frontispiece. 

The  Frame. — The  general  appearance  of  the  Hanriot  is  very 
trim  and  shipshape.  The  central  fuselage  is  built  like  a  racing 
skull,  and  is  very  light  and  strong.  This  construction  does  away 
with  the  large  amount  of  cross-wires,  etc.  The  main  spars  for  the 
planes  are  made  of  wood  in  three  layers  and  are  3  inches  deep 


128 


MONOPLANES    AND    BIPLANES 


and  iy2,  wide.  The  skids  are  fixed  at  the  bottom  of  an  A-type 
frame,  the  upper  part  of  the  A  forming  a  triangular  frame  above 
the  planes,  to  which  the  latter  are  fastened  by  stout  wires. 

The  Supporting  Plane. — The  plane  is  divided  in  half.  The 
halves  are  braced  from  the  central  frame,  and  set  at  a  slight  di- 
hedral angle.  Their  corners  are  rounded.  The  section  is  medium- 


C    ) 


PLAN  AND  ELEVATION  OF  THE  HANRIOT  ONE-PASSENGEH  MONOPLANE 

ly  thick  and  rather  evenly  curved,  the  greatest  camber  being  near 
the  center.  The  spread  is  29%  feet,  the  depth  7  feet,  and  the 
surface  area  183  square  feet. 

Tlie  Elevation  Rudder. — Hinged  to  the  rear  of  the  horizontal 
tail  are  two  flaps  serving  as  the  elevation  rudder.     All  the  rud- 


I 
MONOPLANES    AND   BIPLANES  129 

ders  in  the  Ilanriot  are  noteworthy  for  their  small  size.  These 
rudders  are  operated  by  a  lever  in  the  aviator's  right  hand,  which 
is  pushed  forward  for  descent  and  pulled  in  for  ascent.  The 
rudders  are  2  feet  deep. 

The  Direction  Rudder. — A  very  small  single  surface,  placed 
between  the  two  elevation  rudder  flaps,  is  the  direction  rudder. 
It  is  operated  by  a  foot  bar,  as  on  many  of  the  French  mono- 
planes. 

Transverse  Control. — Warping  of  the  planes  is  used  for  trans- 
verse control.  The  rear  spars  are  hinged,  to  permit  of  this.  The 
lever  controlling  this  is  in  the  aviator's  left  hand,  and  when  pulled 
to  the  right,  elevates  the  left  side  of  the  machine.  The  control  sys- 
tem is  described  in  Chapter  XIII. 

Tail. — The  horizontal  empennage,  non-lifting,  resembles  very 
much  that  on  the  Antoinette.  A  small  triangular  vertical  em- 
pennage placed  above  the  horizontal  one  is  provided.  The  tail 
surface,  however,  is  remarkable  for  its  small  size.  The  skiff-like 
frame  does  not  come  to  a  point  on  this  type,  although  on  the  larger 
type  it  does.  The  total  length  is  26  feet.  The  tail  is  8  feet  wide, 
and  in  all  9  feet  long. 

Propulsion. — A  four-cylinder  50  horse-power  Clerget  is  usually 
provided  and  drives  at  1,203  r.p.m. ;  a  Chauviere  propeller,  7.2 
feet  in  diameter  and  3.8  feet  pitch,  is  placed  about  3  feet  in  front 
of  the  main  plane.  An  eight-cylinder  E.  N.  V.  40  horse-power 
motor  is  also  used. 

The  Seat  is  placed  as  in  the  Antoinette,  and  is  very  comfortable. 

Mounting. — The  mounting  is  mainly  on  two  strong  skids  at 
the  front  supported  by  three  uprights  of  the  A-type  frame  work; 
the  axles  of  the  two  wheels  are  carried  onjvertical  guides,  and  are 
suspended  by  rubber  springs  anchored  to  the  skids.  There  is  a 
small  skid  at  the  rear. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  approximately  51  miles  per  hour.  The  total 
weight  is  760  pounds;  15.2  pounds  being  lifted  per  horse-power, 
and  4.15  per  unit  of  surface.  The  aspect  ratio  is  4.2  to  1. 

There  is  a  larger  passenger-carrying  type  of  this  machine  in 


130  MONOPLANES   AND   BIPLANES 

which  the  spread  is  43  feet  and  the  surface  300  square  feet.  The 
total  weight  is  1,120  pounds,  and  the  speed  somewhat  less  than 
the  small  type. 

References. — Aero,  1910,  November  2nd,  p.  350 :  October 
12th,  1910,  p.  291;  Aeronautics  (Brit.),  September,  1910, 
p.  126 ;  L'Aerophile,  July  15th,  1910,  p.  317 ;  V.  Quittner 
and  A.  Vorreiter,  Zeit.  fur  Flug.  u  Motor.,  November  26th, 
1910 ;  Flight,  1909,  Novfctober  20th,  p.  740  ;  Flight,  1910,  De- 
cember 3rd,  p.  986. 

10.      THE  NIEUPORT  MONOPLANE 

This  extraordinary  monoplane  attracted  a  great  deal  of  attention 
abroad  during  1910  by  its  repeated  flights  at  a  speed  of  52l/2 
miles  an  hour  with  a  small  18  to  20  horse-power  engine.  It  is 
noted  for  the  extreme  simplicity  of  its  design  and  the  finish  ex- 


VIKXV   OF   THE   1910  NIEUPORT   MONOPLANE  FROM 

BEHIND,  SHOWING  THE  TAIL,  FISH-LIKE 

BODY,  AND  WINGS 

hibited  in  its  structure.  It  resembles  more  the  new  R.  E.  P., 
monoplane  than  any  other  type,  but  is  much  smaller.  An  unusual 
feature  is  the  almost  complete  manner  in  which  the  aviator  is 
inclosed  in  the  large  fusiform  hull.  At  Rheims  in  1910  this, 
type  was  flown  by  Niel,  Nogues.  and  Nieuport. 

The  Frame. — The  central  framework  is  of  wood,  steel  tube, 
and  steel  wire  construction;  and  is  completely  inclosed  except  the.- 
seating  space  for  the  aviator. 


MONOPLANES    AND    BIPLANES 


131 


The  Supporting  Plane. — The  plane  is  very  strongly  built  and 
is  divided  into  two  halves,  each  braced  by  only  four  cables  from 
the  central  frame.  The  sectional  curvature  is  quite  flat  and  of 
even  thickness.  The  head  resistance  of  the  framing,  planes,  and 
body,  due  principally  to  the  reduction  in  the  number  of  cross 
wires,  is  extremely  low.  The  supporting  plane  has  a  spread  of 
271/2  fee^  a  maximum  chord  of  6l/2  feet,  and  an  area  of  150  square 
feet 


PLAN  AND  ELEVATIONS  OF  THE  ONE-PASSENGER  20-H.  P. 
NIEUPORT  MONOPLANE 

The  Elevation  Rudder. — At  the  rear  are  the  rudders,  the  two 
small  horizontal  surfaces  serving  to  control  the  elevation.  They  are 
manipulated  by  the  forward  and  back  motion  of  the  steering 
column  as  generally  installed  on  French  machines. 

The  Direction  Rudder. — A  small  vertical  surface  at  the  rear 


132 


MONOPLANES    AND   BIPLANES 


between  the  two  flaps  of  the  elevation  rudder,  as  on  the  Hanriot, 
is  the  direction  rudder.  It  is  operated  by  turning  the  steering 
wheel  mounted  on  the  control  column.  A  biplane  direction  rudder 
was  formerly  used,  but  has  been  discarded. 

Transverse  Control. — The  planes  are  warped  in  the  usual  man- 
ner, the  control  being  by  foot  pedals  as  on  the  M.  Farman  and 
Voisin  "Bordeaux/'  a  type  of  control  which  is  now  coming  into 
general  use  abroad. 

Tail. — A  bird-like  tail,  consisting  of  a  tapering  horizontal  em- 
pennage, is  provided.  There  is  no  vertical  empennage,  but  the 
vertical  sides  of  the  large  inclosed  body  fulfill  this  purpose.  A 
horizontal  lifting  tail  is  provided  on  some  of  the  types. 


THE  TAIL  OF  THE  1910  NIEUPORT  MONOPLANE 

On  recent  types,  only  one  surface  is  used  for  steering ;  the 
elevation  rudder  consists  of  two  small  flaps  and  the  keel 
shown  here  is  discarded. 

Propulsion. — One  of  the  most  interesting  features  of  the  Nieu- 
port  is  the  manner  in  which  the  two-cylinder  Darracq  18  to  20 
horse-power  motor  is  mounted.  The  front  spars  of  the  frame 
project  out  beyond  the  inclosed  body,  and  are  joined  together  on 
either  side  by  a  steel  joint.  On  the  end  of  each  cylinder  is  a 
pressed  steel  ring.  These  rings  are  fitted  on  the  projecting  steel 
joint  end  of  the  spars,  and  the  motor  there  suspended.  The  motor 
drives  direct  a  two-bladed  Chauviere  propeller,  6%,  feet  in  diam- 
eter, 4  feet  pitch,  at  1,200  r.p.m. 


MONOPLANES   AND   BIPLANES  133 

The  Seat  is  placed  about  on  the  center  line  of  the  planes,  the 
aviator's  head  being  flush  with  the  top  of  the  body. 

The  Mounting  is  mainly  on  two  wheels,  with  a  strong,  springy 
axle,  and  a  large  skid  at  the  center. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  52%  miles  an  hour.  The  total  weight  is  670 
pounds;  35  pounds  are  lifted  per  horse-power,  and  4.5  pounds  per 
square  foot  of  surface.  The  aspect  ratio  is  4.23  to  1. 

There  is  a  two-passenger  type  of  this  machine,  34  feet  spread, 
and  having  an  area  of  194  square  feet.  The  total  weight  is  about 
860  pounds,  and  a  Gnome  53  horse-power  motor  is  used. 

References. — Aero,  1910,  November  2nd,  p.  350  ;  November 
30th,  p.  425  ;  Flight,  July  16th,  1910,  p.  551 ;  December  10th, 
1910 ;  Aerophile,  July  15th,  1910,  p.  317  ;  Vorreiter,  A.  "Jahr- 
buch,  1911." 

11.      THE  PFITZNER  MONOPLANE 

Iii  the  early  part  of  January,  1910,  the  monoplane 
designed  by  Mr.  A.  L.  Pfitzner  and  built  at  the  Curtiss  aeroplane 
factory  at  Hammondsport,  N.  Y.,  was  completed  and  flown.  The 
first  flights  were  short,  due  largely  to  the  inexperience  of  the 
aviator,  Mr.  Pfitzner,  but  the  monoplane  is  considered  by  many  to 
be  a  very  promising  type. 

This  aeroplane  is  a  distinct  departure  from  all  other  mono- 
planes in  the  placing  of  the  motor,  aviator,  and  rudders,  and  in 
the  comparatively  simple  and  efficient  method  of  transverse  con- 
trol by  sliding  surfaces,  applied  here  for  the  first  time. 

The  Frame. — The  framework  is  largely  a  combination  of  nu- 
merous king-post  trusses  with  spruce  compression  members  and 
wire  tension  members.  The  framework  is  open  throughout,  thus 
enabling  quick  inspection  and  easy  repairs.  The  chassis  at  the 
center  is  mainly  of  steel  tubing. 

The  Supporting  Plane. — The  main  supporting  plane  at  a 
5-deg.  dihedral  angle  consists  of  two  main  beams  across  which 
are  placed  spruce  ribs.  The  surface  is  made  of  Baldwin  vulcanized 
silk,  of  jet  black  color,  tacked  to  the  top  of  the  ribs  and  laced  to 
the  frame.  The  curvature  of  the  surface  is  slight  and  is  designed 


134 


MONOPLANES    AND    BIPLANES 


25^:_ ill 


PLAN  AND  ELEVATIONS  OP  THE  PFITZNER  MONOPLANE 


MONOPLANES    AND    BIPLAN'ES 


135 


for  high  speed.  The  spread  is  31  feet,  the  depth  6  feet,  and  the 
surface  area  186  square  feet. 

The  Direction  Rudder. — The  direction  rudder,  a  rectangular 
surface,  is  placed  at  the  front  and  has  an  area  of  6  square  feet. 
It  is  operated  by  wires  leading  to  the  bracket  underneath  the  con- 
trolling column.  By  turning  this  column  to  either  side  the  aero- 
plane turns  to  that  side. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  a 
single  surface  17  square  feet  in  area  placed  also  at  the  front.  It 
is  operated  by  wires  leading  to  the  lever  at  the  side  of  the  con- 


THE  PFITZNER  MONOPLANE 
A  near  view  of  the  chassis,   motor  and  controls. 

trolling  column.  By  moving  this  column  forward  or  backward, 
the  elevation  rudder  is  caused  to  turn  down  or  turn  up  respectively. 
Transverse  Control. — The  framework  of  the  main  surface  is 
carried  out  30  inches  on  either  end  of  the  surface,  and  affords 
a  place  for  the  rail  upon  which  the  auxiliary  sliding  surfaces  move. 
These  sliding  surfaces,  or  "equalizers"  are  each  l2l/2  square  feet 
in  area,  and  when  normal  project  15  inches  beyond  the  end  of 


136  MONOPLANES    AND    BIPLANES 

the  surface  on  either  side.  They  are  connected  by  a  wire  to 
each  other,  and  a  long  cable  running  to  each  end  through  a  pulley 
connects  them  to  the  steering  wheel.  The  control  is  then  as  fol- 
lows :  If  the  right  end  of  the  aeroplane  is  tipped  down,  the  wheel 
supported  on  the  controlling  column  is  turned  away  from  the  low- 
ered side.  This  causes  the  equalizer  on  the  raised  end  to  be  pulled 
in  under  the  main  surface,  while  at  the  same  time  the  one  on  the 
other  end  is  pulled  out.  This  action  merely  decreases  the  sup- 
porting surface  on  the  raised  end  and  increases  that  on  the  lowered 
end,  thus  righting  the  machine. 

Keels.  —  A  horizontal  surface  placed  at  the  rear  acts  as  a  longi- 
tudinal stabilizer.  It  is  10.5  square  feet  in  area,  and  is  fixed 
firmly  to  the  supporting  framework,  10  feet  in  the  rear  of  the 
main  surface. 

Propulsion.  —  A  25  horse-power  Curtiss  4-cylinder  motor  is 
placed  on  the  framework  above  the  plane  and  at  the  rear  of  it. 
The  motor  drives  direct  a  2-bladed  wooden  propeller  6  feet  in 
diameter  and  4.5  feet  pitch  at  1,200  r.p.m.  The  propeller  is  of 
original  design  and  said  to  be  very  efficient. 

The  Seat  for  the  aviator  is  placed  out  in  front  of  the  main 
plane  and  directly  on  the  center  line. 

The  Mounting  is  on  four  small  rubber-tired  wheels,  placed  at 
the  lower  ends  of  the  four  main  vertical  posts  of  the  chassis.  The 
wheels  are  not  mounted  on  springs.  They  are  spaced  by  steel 
tubing  and  are  fitted  with  brakes. 

Weight,  Speed,  Loading  and  Aspect  Ratio.  — 

The  total  weight  in  flight  is  from  560  to  600  pounds.  The 
speed  is  estimated  at  42  miles  per  hour;  24  pounds  are  lifted  per 
horse-power,  and  3.2  pounds  carried  per  square  foot  of  surface. 
The  aspect  ratio  is  5.17  to  1. 

References.  —  Aeronautics,  v.  6,  p.  53,  February,  1910  ;  v.  6, 
p.  82,  March, 


12.      THE  PISCHOF  MONOPLANE    (AUSTRIAN) 

This  monoplane  is  a  distinct  departure  from  usual  practice, 
and  is  particularly  notable  for  the  position    of    its    propeller,  its 


I  < 

MONOPLANES    AND    BIPLANES  137 

low  center  of  gravity,  the  upturned  ends  of  the  plane,  and  the  pro- 
vision of  a  clutch  enabling  the  aviator  to  start  the  motor,  step 
into  the  machine,  and  then  start  the  propeller.  Many  biplanes 
and  monoplanes  were  built  by  M.  Pischof  in  1907  and  1908.  The 
present  type,  with  its  chassis  like  a  motor  car,  has  been  flown  very 
well  this  summer,  and  certainly  incorporates  many  practical  and 
far-sighted  innovations.  Despite  its  low  center  of  gravity,  it  flies 
easily  around  corners.  This  type  is  manufactured  by  the  Auto- 
plan- Werke  in  Vienna,  as  is  also  the  Warchalowski  biplane. 


THE  PISCHOF  MONOPLANE 

A  view  of  the  body,  showing  the  automobile-like  radiator 
and  motor  casing  the  crank  and  the  propeller  which 
is  governed  by  a  clutch. 

The  Frame. — The  wooden  cross-wired  frame  is  everywhere 
painted  with  an  aluminum  mixture,  as  were  the  Wright  machines. 
The  joints  are  very  strong,  and  the  lower  members  are  continued 
out  in  front  to  form  skids.  A  great  many  cross-wires  and  bracing 
wires  are  used,  considerably  complicating  the  structure. 

The  Supporting  Plane. — The  main  surface  is  perfectly  straight 
in  front.  The  rear  edges  are  turned  up  slightly,  as  on  the  Etrich 
IV.  It  is  claimed  that  this  adds  greatly  to  the  stability.  The 
plane  is  braced  from  the  central  frame,  and  its  trailing  edge  is 


138 


MONOPLANES    AND    BIPLANES 


PLAN  AND  ELEVATIONS  OF  THE  PISCHOF  MONOPLANE 


MOXOPLAXKS    AND    BIPLANES 


139 


warpable.     The  spread  is  36  feet,  the  chord  9  feet,  and  the  area 
290  square  feet. 

The  Elevation  Rudder. — A  Bleriot  XI.  type  elevation  rudder 
is  carried  at  the  rear.  The  central  portion  is  rigid,  and  the 
two  outer  portions  movable.  They  are  manipulated  by  the  for- 
ward and  back  movement  of  a  large  lever  in  front  of  the  aviator, 
forward  for  descent,  etc. 


THE  PISCHOF  MONOPLANE  IN  FLIGHT 

The  Direction  Rudder. — Two  identical  surfaces  at  the  rear 
above  the  elevator  are  the  direction  rudders.  They  are  moved  by 
a  foot  lever  and  wires. 

Transverse  Control. — The  transverse  control  is  obtained  by 
warping  the  rear  of  the  planes.  This  is  done  by  the  side-to-side 
motion  of  the  large  control  lever. 

Tail. — In  addition  to  the  fixed  surface  of  the  elevation  rudder, 
there  is  also  a  triangular  surface  at  the  rear.  Both  exert  consid- 
erable lift.  Over  and  under  the  triangular  surfaces  are  small  ver- 
tical keels.  At  the  front  two  sections  of  the  chassis  frame  are 


140  MONOPLANES    AND    BIPLANES 

inclosed,  to  form  vertical  keels_,  which  in  turning  help  to  avoid  the 
effect  of  the  low  center  of  gravity. 

Propulsion. — The  propelling  system  of  the  Pischof  is  one  of 
its  most  radical  features.  The  motor  is  placed  in  front  under 
the  planes  with  a  radiator  in  front  of  it  and  two  seats  in  back 
of  it,  exactly  as  on  an  automobile.  The  motor  of  60  to  70  horse- 
power drives  by  a  shaft,  clutch,  and  chains,  the  single  variable 
pitch  Normale  S^-foot  diameter  propeller,  placed  at  the  center 
and  flush  with  the  rear  of  the  plane.  Here  for  the  first  time  is 
a  practical  and  successful  means  of  providing  a  monoplane  with 
a  propeller  at  the  rear  instead  of  at  the  front.  Gnome,  E.  X.  V., 
and  Daimler  motors  have  been  used. 

Seats. — The  position  of  the  aviator's  seat  and  that  of  his  pas- 
senger is  very  practical,  and  enables  a  clear  view  in  every  direc- 
tion, as  well  as  being  away  from  the  propeller  slip  stream,  etc. 

The  Mounting. — The  mounting  is  on  two  wheels  at  the  front 
fitted  with  springs  and  two  small  wheels  at  the  rear.  The  long 
skids  at  the  front,  really  forming  part  of  the  frame,  are  fitted 
with  small  supplementary  skids. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  high  for  so  large  a  machine,  53  miles  per  hour 
often  being  attained.  The  total  weight  in  flight  is  from  910  to 
1,060  pounds;  1714  pounds  are  lifted  per  horse-power,  and  3.65 
per  square  foot  of  surface.  The  aspect  ratio  is  4  to  1. 

References. — Flight,  July  16th,  1910,  p.  551  ;  November 
19th,  1910,  p.  948  ;  Aircraft,  November,  1910,  p.  328  ;  L'Aero, 
November  17th,  1910 ;  Rv.  de  1'Aviation,  December,  1907 ; 
August  15th,  1908 ;  November  15th,  1908  ;  L'Aerophile,  Novem- 
ber, 1907,  p.  328  ;  Vorreiter,  A.  "Jahrbuch,  1911." 

13.      THE  R.   E.  P.  MONOPLANE    (1909) 

The  old  R.  E.  P.  monoplane  was  considered  by  many  to  be 
one  of  the  most  perfect  types  of  aeroplanes.  Great  finish  was 
exhibited  in  its  construction  and  form,  but  due  probably  to  motor 
troubles  it  never  was  flown  for  any  great  length  of  time.  M.  Pel- 
terie,  the  designer,  is  one  of  the  foremost  aviation  scientists  abroad, 


MONOPLANES    AND    BIPLANES 


141 


THE  R.  E.  P.  1909  MONOPLANE 

Side  elevation  plan  and  front  elevation,  showing  the  negative  dihedral  angle  and 
wheels  at  ends  of   plane. 


142  MONOPLANES    AND   BIPLANES 

and  previous  to  his  experience  with  this  machine  he  conducted 
a  series  of  gliding  experiments  of  great  interest. 

The  Frame. — The  central  frame,  somewhat  similar  in  shape 
to  a  bird's  body,  was  made  largely  of  steel  tubing,  and  was  quite 
short.  All  exposed  parts  were  covered  with  Continental  cloth. 

The  Supporting  Plane. — The  main  surface  was  particularly 
strong  and  solid,  and  was  made  of  steel  tubing  carrying  wooden 
ribs  covered  with  Continental  cloth.  The  curvature  was  very  sim- 
ilar to  that  of  a  bird's  wing,  and  transversely  the  surface  curved 
downward  dihedrally  from  the  center.  There  was  very  little  brac- 
ing necessary.  The  spread  was  35  feet,  the  depth  6.1  feet,  and  the 
area  214  square  feet. 

The  Direction  Rudder. — The  rudder  for  steering  from  side  to 
side  consisted  of  a  vertical  rectangular  surface  of  8  square  feet 
area,  placed  below  the  central  frame  at  the  rear.  It  was  operated 
by  the  side-to-side  motion  of  the  lever  at  the  aviators  right  hand. 
To  turn  to  any  side  the  lever  was  inclined  to  that  side. 

The  Elevation  Control. — There  was  no  elevation  rudder  in 
the  1909  Pelterie  monoplane,  the  elevation  of  the  machine  being 
regulated  by  changing  the  incidence  of  the  main  plane  itself.  To 
ascend,  for  example,  the  aviator  pulled  the  lever  in  his  left  hand 
toward  him.  This  increased  the  incident  angle  of  the  plane  and 
the  consequent  increase  of  lift  caused  the  machine  to  rise. 

Transverse  Control. — Each  half  of  the  main  plane  was  warp- 
able  about  its  base,  and  transverse  equilibrium  was  obtained  by  an 
inverse  warping  of  the  plane.  The  side-to-side  motion  of  the  left- 
hand  lever  controlled  the  warping.  If  the  machine  was  tipped 
down  on  the  right  end  the  lever  was  moved  to  the  left  and  the 
machine  brought  back  to  an  even  keel.  In  turning  to  either  side 
both  the  left-hand  lever  controlling  the  warping  and  the  right- 
hand  lever  controlling  the  direction  rudder  were  simultaneously 
moved  to  that  side.  This  was  a  very  effective  controlling  system. 

Keels. — Vertical  and  horizontal  keels,  consisting  of  gradually 
tapering  surfaces,  were  fixed  to  the  frame  and  aided  in  preserving 
stability.  The  rear  horizontal  keel,  shaped  like  a  bird's  tail,  had 
an  area  of  20  square  feet. 


MONOPLANES    AND    BIPLANES  143 

Propulsion. — A  7-cylinder  35  horse-power  E.  E.  P.  motor, 
placed  at  the  front,  drove  direct  a  four-bladed  aluminum  and  steel 
propeller  at  900  r.p.m.  The  diameter  of  the  propeller  was  6.6 
feet,  and  the  pitch  5  feet. 

The  Seat  was  placed- in  the  frame,  and  protected  on  all  sides. 
The  aviator's  shoulders  were  flush  with  the  surface. 

The  Mounting  was  mainly  on  a  large  single  wheel  with  an 
oleo-pneumatic  spring  in  the  center  at  the  front  and  a  smaller 
one  in  the  same  center  line  at  the  rear.  When  first  starting  the 
aeroplane  was  inclined,  resting  on  one  end  of  the  plane,  on  each 
end  of  which  a  wheel  was  placed. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  was  from  900  to  970  pounds.  The  speed 
Avas  39  miles  per  hour;  27  pounds  were  lifted  per  horse-power,  and 
4.4  pounds  carried  per  square  foot  of  surface.  The  aspect  ratio 
was  5.75  to  1. 

References. — Soc.  des  Ing.  Civ.,  v.  2  (1908),  p.  13;  Boll. 
Soc.  Aer.  Ital.,  v.  6,  pp.  67,  288 ;  Aerophile,  v.  15,  p.  331 ; 
v.  16,  p.  226;  v.  17,  p.  33;  Flight,  v.  1,  pp.  19,  360;  Aero- 
nautical  Jour.,  v.  13,  p.  64  ;  Zeit.  fur  Luftschiff,  v.  12,  p.  458  ; 
Aeronautics,  v.  4,  p.  21  ;  La  Prance  Aerienne,  v.  14,  Nos.  7,  9  ; 
Zeit.  Ver.  Deut.  Ing.,  v.53,  p.  1760  ;  Genie  Civil,  v.  55,  p.  346. 

-      .'_'."•?•    -  "--:•       '*.y  T 

14.    THE  R.  E.  P.  1911  (ONE-SEAT) 

The  newest  product  of  M.  Esnault-Pelterie  differs  radically 
from  the  older  type  in  the  method  of  elevation  control  and  m  the 
construction  of  the  tail  as  well  as  in  propeller,  motor,  etc.  This 
type  is  built  in  two  sizes  (one  or  two  seater)  and  preserves  in 
great  measure  the  graceful  lines  of  its  predecessors.  In  view  of 
the  recent  excellent  flights  of  Laurens  and  Bournique,  with  and 
without  passenger,  and  because  of  its  high  speed,  reliability  and 
stability  the  scarlet  bird-like  E.  E.  P.  has  at  last  taken  its  rank 
among  the  very  best  flying  machines  of  the  day.  Bournique  on 
the  small  E.  E.  P.  flies  at  60  miles  an  hour,  and  only  recently  M. 
and  Mine.  Laurens  .established  a  passenger  speed  record.  Bour- 
nique on  December  31st,  1910,  in  competition  for  the  Micheljn 
cup,  flew  this  type  331  miles. 


144 


MONOPLANES    AND    BIPLANES 


The  Frame. — The  splendid  non-soldered  steel-tube  construction 
of  the  frame  gives  great  strength  and  durability.  In  the  minutest 
details  the  R.  E.  P.  exhibits  excellent  workmanship.  All  joints  are 
welded. 

The  Supporting  Plane. — The  plane  is  similar  in  shape  and 
structure  to  the  old  R.  E.  P.  It  is  fixed  to  the  central  frame  by 


Courtesy  of  "Flight." 


THE  FRONT  OF  THE  R.  E.  P.  (1911) 


Showing   the   landing   chassis,    motor,    propeller    and    part    of   body.      The    wheel 

axles  are  pivoted  to  the  central  skid.     The  skid  itself 'is 

fitted  with  a  strong  spring. 


MONOPLANES    AND    BIPLANES 


145 


four  cables,  and  its  incidence  cannot  be  changed  as  formerly.  It 
is.  however,  warpable.  The  two  halves  are  set  at  an  upward 
dihedral  angle,  and  not  turned  down  as  on  the  old  type.  The 
material  used  is  a  red  vulcanized  cotton  fabric.  The  cables  used 


4O '     9" 


SIDE  ELEVATION,  PLAN  AND  FRONT   ELEVATION  OF  THE  1911   ONE-SEAT   R.  E.   P. 


14G 


MONOPLANES    AND    BIPLANES 


to  support  the  frame  are  more  numerous,  and  the  plane  is  braced 
both  above  and  below.  The  frame  consists  of  two  main  steel 
laterals  with  ribs  having  an  I-section.  The  spread  is  42  feet,  the 
mean  chord  6%,  feet,  and  the  area  270  square  feet. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  two 
flaps  on  the  end  of  the  horizontal  tail.  The  alteration  of  the  in- 
cidence of  the  main  planes  to  control  elevation  is  entirely  dis- 
carded in  this  type.  The  elevators  are  controlled  by  the  to-and- 
fro  motion  of  the  left-hand  lever. 


THE   1911   R.   E.  P.   AS   SEEN  FROM   BEHIND,   SHOWING  THE 

REAR  TAIL  AND  RUDDERS,  AND  AT  TIIK  FRONT, 

THE  MAIN  PLANE 

The  Direction  Rudder. — Two  small  planes  at  the  rear,  moved 
jointly,  serve  as  the  direction  rudder.  They  are  operated  either 
by  the  side-to-side  motion  of  the  right-hand  lever,  as  on  the  former 
type,  or  by  an  ordinary  foot  pedal. 

Transverse  Control. — The  widely  used  warping  method  of 
transverse  control  is  here  employed.  The  warping  is  controlled 
by  the  side-to-side  motion  of  the  left-hand  lever. 

Tail. — The  rear  is  greatly  altered  in  form.  The  vertical  em- 
pennage is  very  much  smaller,  as  is  also  the  horizontal  non-lifting 
tail.  The  entire  tail  can  readily  be  dismounted. 

Propulsion. — A  five-cylinder  55  horse-power  R.  E.  P.  motor  is 
installed  at  the  front,  and  the  recent  success  of  this  type  is  largely 


MONOPLANES   AND   BIPLANES  147 

due  to  the  great  improvements  in  this  motor.  The  two-bladed 
8^4-foot  wooden  Regy  propeller  is  driven  direct  at  a  speed  varying 
between  500  and  1,250  r.p.m.  The  four-bladed  propeller  formerly 
used  is  discarded. 

The  Mounting. — The  mounting  is  altogether  different  from 
the  old  type,  and  is  very  simple.  The  single  central  wheel  is  aban- 
doned, and  in  its  stead  is  a  large  skid  fitted  by  a  springy  telescop- 
ing steel  tube  to  the  main  fuselage.  A  steel-tube  frame  and  axle 


THE  KLDDERS  AND  TAIL  OF  THE  1911  R.  E.  P. 

also  support  two  rubber-tired  wheels,  one  on  either  side  of  this 
skid,  fitted  with  rubber  rope  springs.  A  small  skid  is  fixed  at 
the  rear.  No  wheels  are  placed  on  the  ends  of  the  plane. 

The  Seat  is  placed  as  formerly,  and  is  well  protected. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  almost  60  miles  an  hour.  The  total  weight  is 
from  1,180  to  1,240  pounds;  22.5  pounds  are  carried  per  horse- 
power, and  4.6  per  square  foot  of  surface.  The  aspect  ratio  is 
6.5  to  1. 

References. — "Neve  Flugzeuge  in  Paris,"  Zeit.  fur  Plug,  u 
Motor,  November  26th,  1910;  Flight,  1910,  October  22nd,  p. 
862  ;  October,  29th,  p.  880 ;  L'Aero,  1910,  October  28th ;  De- 
cember 1st ;  Aero,  1910,  October  26th  ;  November  2nd,  p.  350 ; 
November  16th ;  Flugsport,  October  19th,  1910. 


148  MONOPLANES    AND   BIPLANES 

15.     THE  SANTOS-DUMONT  MONOPLANE 

The  first  sustained  flight  of  a  motor  aeroplane  in  Europe  was 
made  by  M.  Santos-Dumont  on  November  12th,  1906,  in  a  biplane 
of  his  design.  In  1907  he  began  work  on  a  monoplane,  and  after 
much  alteration,  has  finally  evolved  the  highly  successful  and  in- 
teresting little  monoplane,  the  "Demoiselle."  This  is  the  smallest 
aeroplane  in  use  to-day.  Many  machines  of  this  type  are  being 
flown  abroad,  and  their  simplicity  renders  them  quite  popular. 

The  Frame. — The  frame,  which  narrows  toward  the  rear,  is 
made  of  bamboo  and  steel  joints,  with  several  members  of  metal 
tubinsr. 


AUDEMARS  OX  HlS  "DEMOISELLE"  ABOUT  TO  START  OX  A  SPEEDY 
LAP  AT  BELMOXT  PARK 

The  propeller,  at  the  front,  is  rotating  so  fast  that  only  the 
hub  is  visible.  Note  how  the  smoke  is  blown  back  by  the 
propeller  draught. 

The  Supporting  Plane. — The  supporting  plane  has  both  sides 
slightly  turned  up  from  the  center,  and  consists  of  a  double  layer 
of  silk  stretched  very  tightly  over  bamboo  ribs.  The  plane  is 
braced  by  wires  to  the  central  frame.  The  curvature  is  approxi- 
mately the  arc  of  a  circle.  The  spread  is  18  feet,  the  depth  6.56 
feet  and  the  area  113  square  feet. 

The  Direction  Rudder  and  the  Elevation  Rudder. — The  two 
rudders  are  combined  at  the  rear  into  two  fan-shaped  surfaces,  one 


MONOPLANES   AND   BIPLANES 


149 


vertical  and  the  other  horizontal.  They  are  pivoted  on  a  single 
universal  joint.  The  elevation  rudder  is  21  square  feet  in  area, 
while  the  direction  rudder  is  somewhat  less.  A  lever  at  the  avi- 
ator's right  hand  controls  the  movement  of  the  elevation  rudder, 


SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVA- 
TION  OF   THE   SANTOS 

MONOPLANE  "DEMOISELLE" 


while  a  small  steering  wheel  at  the  aviator's  left  hand  controls 
the  direction  rudder.  To  rise  the  tail  is  moved  up,  while  to  turn 
to  the  right  it  is  moved  to  the  right. 


150 


MONOPLANES    AND   BIPLANES 


Transverse  Control. — Transverse  control  is  effected  in  the 
Santos-Dumont  by  the  warping  of  the  main  planes.  This  action 
is  governed  by  a  lever  at  the  back  of  the  aviator,  and  which  fits 
into  a  socket  sewed  on  his  coat.  If  the  aeroplane  should  suddenly 


SANTOS  DUMONT  TRAVELLING  ACROSS   COUNTRY 

tip  up  on  the  left,  then  the  aviator,  by  moving  quickly  to  the  left, 
pulls  down  and  increases  the  angle  of  incidence  of  the  right  side 
of  the  plane.  The  ribs  of  the  plane  are  flexible  in  this  machine. 

Keels. — There  are  no  keels  in  the  Santos-Dumont  monoplane. 

Propulsion. — A  30  horse-power  water-cooled  Darracq  2-cylin- 
der  motor  placed  on  the  top  of  the  plane  at  the  front  drives  direct 


MONOPLANES    AND    BIPLANES  151 

a  2-bladed  Chauviere  wooden  propeller  6.9  feet  diameter  and  6  feet 
pitch  at  1,400  revolutions  per  minute.  Clement-Bayard  and  Pan- 
hard  motors  are  also  used  on  this  type  of  monoplane. 

The  Seat  is  a  strip  of  canvas  placed  across  the  frame  below 
the  main  plane. 

The  Mounting  consists  of  two  wheels  at  the  front  and  a  skid 
at  the  rear.  Xo  springs  are  provided  on  the  wheels. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  330  to  370  pounds;  the  speed  is  oo 
miles  per  hour;  12  pounds  are  lifted  per  horse-power  and  3.1 
pounds  per  square  foot  of  surface.  The  aspect  ratio  is  3  to  1. 

References. — Flight,  v.  1,  p.  603  ;  Sci.  AMERICAN  SUP.,  v. 
68,  p.  317  ;  Sci.  AMERICAN,  v.  97,  p.  445  ;  v.  99,  p.  433  ;  Aero- 
phile,  v.  15,  p.  313;  v.  16,  p.  468;  v.  17,  pp.  435,  488; 
L'Aviation  111.,  No.  34,  p.  3  ;  La  Prance  Aerienne,  v.  14,  p. 
608  ;  Omnia,  No.  200,  p.  281 ;  Encyl.  d'Av.,  v.  1,  p.  126  ;  Vor- 
reiter,  A.,  "Motor  Flugapparate"  :  Zeit.  Ver.  Deut.  Ing.,  v.  53, 
p.  1762;  Genie  Civil,  v.  55,  p.  466. 

1G.       THE   SOMMER  MONOPLANE 

M.  Eoger  Sommer  has  recently  brought  out  a  monoplane  which 
follows  regulation  lines,  but  is  exceptionally  strong.  In 
this  machine  M.  Sommer  at  Douzy  has  already  made  many 
creditable  flights.  The  general  aspect  reminds  one  of  a  Bleriot 
fuselage  mounted  on  a  biplane  chassis. 

The  Frame. — The  central  frame  fuselage  is  of  the  ordinary 
wood  and  wire  construction  covered  for  some  distance  under  the 
wings.  There  is  a  Bleriot  XI.  type  frame  above  the  plane  to  which 
it  is  braced. 

The  Supporting  Plane. — The  plane  is  divided  into  two  halves 
set  at  a  dihedral  angle,  braced  by  wires  to  the  central  frame,  and 
strongly  resembling  the  Bleriot.  The  spread  is  341/2.  feet,  the 
chord  5%  feet,  and  the  area  183  square  feet.  The  main  transverse 
member  of  the  frame  of  the  planes  is  a  huge  I-beam  of  wood. 

The  Elevation  Rudder. — Two  flaps  fitted  on  the  trailing  end 
of  a  weight-carrymg  horizontal  empennage,  form  the  elevation 
rudder.  They  are  controlled  by  a  large  lever  as  on  the  Sommer 
biplane.  All  control  wires  are  duplicate 


152 


^MONOPLANES    AND    BIPLANES 


The  Direction  Rudder. — A  single  surface  placed  between  the 
two  flaps  of  the  elevator  serves  as  the  direction  rudder,  and  is 
moved  by  means  of  a  foot  pedal  in  the  usual  manner. 


THE  SOMMER  MONOPLANE 
Note  the  splendid  landing  chassis. 


MONOPLANES    AND    BIPLANES  153 

Transverse  Control. — The  planes  are  warped  by  means  of  the 
side-to-side  motion  of  the  large  control  lever,  a  movement  to  the 
left  causing  the  right  side  to  ascend. 

Propulsion. — A  50  horse-power  seven-cylinder  Gnome  motor  is 
placed  at  the  front  and  almost  completely  boxed  in.  It  drives 
direct  a  two-bladed  "Bapid"  propeller,  8.3  feet  in  diameter,  at 
1,200  r.p.m. 

Mounting. — The  mounting  is  on  two  main  skids  supported  DV 
framework  to  the  fuselage,  and  across  which  is  fitted  an  axle  with 
rubber  springs  and  carrying  a  rubber-tired  wheel  at  each  end.  At 
the  rear  is  a  cane  skid. 

Fpeed,  Weight,  Loading  and  Aspect  Ratio* — 

The  speed  is  about  54  miles  an  hour.  The  total  weight  is  690 
pounds,  making  the  pounds  carried  per  horse-power  14,  and  the 
pounds  per  unit  surface  3.8.  The  aspect  ratio  is  6.2  to  1. 

References. — Aero,  1910,  October  26th,  November  2nd ;  Zeit. 
fur  Flug.  und  Motor,  1910,  November  12th,  p.  278  ;  November 
20th. 


Courtesy  of  "Flight  " 

THE  TELL i EII  MONOPLANE 

17.      THE  TELLIER   MONOPLANE 

The  Tellier  monoplane  flown  by  Dubonnet  was  so  manageable 
that  he  obtained  his  pilot's  license  on  his  fourth  outing,  and  oc- 
cupied the  commissioners  only  half  an  hour.  Shortly  thereafter 


MONOPLANES    AND   BIPLANES 


SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION  OF  THE  TELLIER  MONOPLANE 


MONOPLANES    AND    BIPLANES  155 

he  made  a  wonderful  flight  over  Paris,  and  since  then  Dubonnet 
as  well  as  others  have  shown  the  Tellier  to  be  a  peculiarly  strong 
and  reliable  machine.  It  is  very  much  like  the  other  French  mono- 
planes in  general  aspect,  but  differs  considerably  in  the  shape  of 
the  tail,  frame-work,  etc. 

The  Frame. — The  frame  is  a  very  light  and  strong  wood  and 
cross-wire  construction,  and  resembles  the  Bleriot  frame.  At  the 
center  between  the  two  halves  of  the  plane  is  a  large  frame  mast, 
and  this,  with  the  struts  out  on  the  plane,  makes  the  bracing  very 
similar  to  the  Antoinette. 

The  Supporting  Plane. — The  plane  is  divided  into  two  halves 
set  at  a  small  dihedral  angle,  and  more  solidly  built  up  with 
wooden  ribs  and  spars  than  is  customary.  The  planes  are  there- 
fore exceptionally  strong.  They  are  mediumly  curved,  and  about 
3  inches  thick  at  the  center.  The  planes  are  very  strongly  braced, 
and  are  covered  on  both  sides.  The  spread  is  29%,  feet,  the  chord 
(maximum),  7%  feet,  and  the  surface  area,  220  square  feet.  A  two- 
passenger  type  of  this  machine  is  built,  in  which  the  spread  is 
383/4  feet,  the  chord  8  feet,  and  the  area  280  square  feet. 

The  Elevation  Rudder. — At  the  rear  is  a  trapezoidal-shaped 
horizontal  keel,  and  hinged  to  the  rear  of  this  is  the  single-sur- 
face elevation  rudder.  Several  different  types  of  control  have 
been  used,  the  most  common  being  a  Bleriot  cloche,  on  which  the 
wheel  moves.  To-and-fro  motion  is  for  elevation  or  depression. 

The  Direction  Rudder. — The  single  direction  rudder  at  the 
rear  is  placed  above  the  elevation  rudder.  It  is  operated  by  a 
steering  wheel  mounted  on  the  Bleriot  type  cloche,  and  turned  as 
usual,  clockwise  for  a  turn  to  right. 

Transverse  Control. — The  planes  are  warped  by  the  side-to- 
side  motion  of  the  cloche,  as  usually  done. 

Tail. — Beside  the  horizontal  tail  surface  already  mentioned, 
there  is  a  small  triangular  vertical  keel  just  in  front  of  the  direc- 
tion rudder. 

Propulsion. — On  the  small  type  a  four-cylinder  Panhard  45 
horse-power  motor  is  used,  and  drives  direct  a  two-bladed  wooden 
propeller  8  feet  in  diameter.  On  some  of  the  larger  types  a  six- 


156  MONOPLANES    AND    BIPLANES 

cylinder  60  horse-power  Panhard  is  used.     li.  E.  P.  motors  are 
also  fitted. 

Mounting. — This  machine  is  mounted  on  three  wheels,  two  at 
the  front  and  one  smaller  one  at  the  rear.  The  two  at  the  front 
are  mounted  on  springs  and  on  an  elaborate  chassis. 

The  Seat  is  comfortably  placed  near  the  rear  of  the  main  sur- 
face. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  53  miles  an  hour.  The  total  weight  is  850  to  900 
pounds ;  19  pounds  are  lifted  per  horse-power,  and  4  per  square 
foot  of  surface.  The  aspect  ratio  is  4.2  to  1. 

References. — Aero,  1910,  October  26th ;  November  2nd,  p. 
350 ;  November  9th,  p.  364  ;  Flight,  1910,  August  6th,  p.  621  ; 
September  17th  p.  754  ;  p.  759 ;  October  29th,  p.  882  ;  Decem- 
ber 3rd,  p.  991 ;  L'Aerophile,  1910,  March  22nd,  p.  151 ;  July 
15th,  p.  317. 


THE  VALKYRIE  MONOPLANE 
18.       THE  VALKYRIE   MONOPLANE 


This  interesting  aeroplane,  designed  and  built  by  the  Aeronaut- 
ical Syndicate,  Ltd.,  in  England,  is  so  distinct  a  departure  from 
usual  monoplane  practice,  that  it  has  excited  a  great  deal  of  com- 
ment. Many  excellent  flights  have  already  been  made  on  this 


MONOPLANES    AND    BIPLANES 


157 


"All-British"  machine,  and  it  is  speedily  taking  rank  among  the 
prominent  types. 

The  Frame. — A  very  fine  quality  of  Honduras  mahogany  is 
used  almost  exclusively  in  the  framework.  The  main  members  of 
the  frame  are  two  very  long  skids,  upon  which  the  rest  of  the 


SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION  OF  THE  VALKYRIE  MONOPLANE 


158  MONOPLANES    AND   BIPLANES 

frame  is  built  up.  These  skids  are  wide  apart,  and  take  the  place 
of  a  central  chassis. 

The  joints  of  the  frame  are  made  of  aluminum  and  are  very 
neat. 

The  Supporting  Plane. — The  main  plane  is  made  in  three 
sections,  the  one  between  the  frames  and  back  of  the  propeller 
having  a  similar  chord  and  less  incidence  than  the  other  sections 
because  of  its  position  in  the  slip  stream  of  the  propeller.  The 
two  outer  sections  of  the  plane  are  turned  up  slightly,  giving  a 
dihedral  angle  effect.  The  surfaces  are  made  of  one  layer  of  an 
Egyptian  cotton  fabric  stretched  tightly  over  numerous  wooden 
ribs.  The  plane  is  braced  by  cables  to  the  struts  and  frame  of 
the  central  section.  The  spread  is  32  feet,  the  chord  G1/^  feet,  and 
the  surface  area  190  square  feet. 

The  Elevation  Rudder. — Out  at  the  front,  under  the  horizontal 
front  fixed  keel  plane,  is  the  single-surface  elevation  rudder.  This 
is  operated  by  wires  leading  to  a  lever  which  is  moved  to  and 
fro,  as  on  the  H.  Farman  biplane.  The  elevator  is  8  feet  wide, 
21/2.  feet  deep,  and  20  square  feet  in  area. 

The  Direction  Rudder. — Two  identical  surfaces  at  the  rear 
serve  as  direction  rudders.  They  are  controlled  by  a  foot  pedal 
or  by  the  side-to-side  motion  of  the  lever,  as  desired. 

Transverse  Control. — Ailerons  fixed  to  the  trailing  edge  of 
the  main  surface  at  either  end  control  the  transverse  balance.  They 
can  be  operated  by  pedals  or  by  the  side-to-side  motion  of  the 
lever,  as  desired.  These  ailerons  are  5  feet  wide  and  2  feet  deep. 

Keels. — There  is  a  large  horizontal  keel  placed  well  out  in 
front,  and  called  the  "leading  plane,"  14  feet  wide  and  3  feet 
deep.  It  exerts  a  considerable  lift,  and  is  set  at  a  greater  inci- 
dent angle  than  the  main  surface,  thus  employing  the  principle  of 
the  dihedral  angle  for  longitudinal  balance.  The  incident  angle 
of  this  plane  can  be  altered  at  will.  There  is  no  rear  tail. 

Propulsion. — A  30  horse-power  Green  engine,  placed  at  the 
center  in  front  of  the  main  plane,  drives  direct  a  T^-foot  pro- 
peller at  900  r.p.m.  The  position  of  the  propeller  is  a  curious 
one,  working  as  it  does  in  a  slot  in  the  framework. 


MONOPLANES    AND    BIPLANES  159 

Mounting. — The  mounting  of  this  machine  on  the  strong  and 
serviceable  skids  is  one  of  its  distinguishing  features,  and  one 
which  has  been  highly  praised.  There  is  little  doubt  that  in  rough 
landings  a  framework  of  this  kind  is  about  as  safe  and  strong  as 
could  be  desired.  It  resembles  the  old  Wright  frame  in  many 
respects.  On  each  skid  at  the  front,  below  the  seat,  is  fitted  a 
pair  of  wheels  attached  by  springs,  and  at  the  rear  are  two  smaller 
wheels. 

The  Seat  is  very  conveniently  placed  out  in  front  of  the  motor 
as  regards  comfort,  but  in  case  of  accident  this  disposition  is 
dangerous. 

The  center  of  gravity  is  very  far  forward,  and  necessitates  a 
considerable  lift  on  the  part  of  the  "leading  plane." 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  is  about  46  miles  an  hour.  The  total  weight  in 
flight  is  670  pounds;  22%  pounds  are  lifted  per  horse-power,  and 
3.5  per  square  foot  of  surface.  The  aspect  ratio  is  5  to  1. 

A  racing  type  "B"  and  a  passenger  type  "C"  are  also  built. 

Inferences. — Flight,  1910,  October  1,  p.  792;  November  5th. 


1(50 


MONOPLANES   AND   BIPLANES 


SEVERAL  BIPLANES  IN  FLIGHT 


CHAPTEE  XI. 

PROMINENT  TYPES  OF  BIPLANES 

The  number  of  biplanes  built  and  under  construction  is  so 
large  that  to  give  anything  like  a  complete  survey  of  the  different 
makes  is  almost  impossible. 

There  are,  however,  at  present  twenty  distinct  types,  to  one  or 
the  other  of  which  almost  all  biplanes  bear  resemblance.  Thus 
the  Howard  Wright,  the  Warchalowski,  and  the  Aviatic,  as  well  as 
many  American  biplanes,  closely  resemble  the  Fannan.  The  Ger- 
man Albatross  biplane  is  merely  a  counterpart  of  the  Sommer,  and 
in  America  there  are  twenty  or  more  successful  "imitations"  of  the 
Curtiss  type,  and  a  few  that  follow  the  Wright.  The  Caudron 
S.  A.  F.  A.,  resembles  the  other  French  "tractor  screw"  biplanes 
in  many  respects,  and  the  Euler  closely  follows  the  Voisin. 

The  twenty  types  of  biplanes  considered  here  are: 

1.  Breguet 

2.  Cody  (1909) 

3.  Cody  (1911) 

4.  Curtiss 

5.  Dufaux 

6.  Dunne 

7.  H.  Farman  (1909) 

8.  H.  Farman  (Michelin) 

9.  Maurice  Farman 

10.  Goupy 

11.  Neale 

12.  Paulhan 

13.  Sommer 

14.  Voisin  (1909) 

15.  Voisin  (Tractor) 

16.  Voisin  (Bordeaux) 


162  MONOPLANES    AND    BIPLANES 

17.  Voisin  (Front  Control,  1911) 

18.  Wright  (1909) 

19.  Wright  (Model  R) 

20.  Wright  (Model  B) 

1.       THE   BUEGUET   BIPLANE 

M.  Louis  Breguet  has  been  experimenting  for  many  years  at 
Douai,  France,  and  has  gradually  evolved,  step  by  step,  one  of  the 
most  perfect  flying  machines  yet  constructed.  It  is  interesting  to 
note  that  the  first  successful  helicopter  to  lift  a  man  was  built  by 
him  in  conjunction  with  M.  Eichet  in  19,07,  the  total  weight  lifted 
being  1,100  pounds.  The  elegance  of  lines  and  the  simplicity  of  his 
new  biplane  have  resulted  only  from  patient  and  diligent  study  of 
the  subject.  This  machine  is  especially  remarkable  for  its  great 
excess  of  lifting  force  and  the  wonderful  steadiness  with  which  it 
"volplanes." 

On  April  8th,  1910,  the  Breguet  biplane  lifted  three  people  at 
once  and  flew  with  such  great  ease,  that  the  attention  of  the 
aviation  world  was  attracted  to  Douai.  At  Eouen,  at  Eheims,  and 
at  many  other  foreign  meetings,  the  Breguet  biplanes,  driven  by 
M.  Breguet  himself  and  by  Bathiat,  not  only  won  many  prizes  for 
passenger  flights,  but  proved  to  be  extremely  speedy  and  reliable. 

During  the  French  Army  Manoeuvres,  M.  Breguet,  with  the 
late  Capt.  Madiot,  made  some  excellent  reconnoitering  trips. 

On  September  1st,  1910,  a  flight  was  made  with  five  persons 
aboard,  the  pilot  and  four  passengers  making  a  total  load  of  750 
pounds.  This  performance  was  exceeded^  by  the  same  machine  a 
few  weeks  later,  when  the  pilot  and  five  passengers  made  an  ex- 
cellent flight,  the  total  load  carried  being  about  860  pounds.  This 
performance,  however,  has  quite  recently  been  exceeded  by  Som- 
mer  and  Bleriot.  On  December  31st,  1910,  the  Breguet  made  a  dis- 
tance flight  of  205  miles. 

The  Frame. — The  Breguet  biplane  is  one  of  the  few  present- 
day  types  in  which  wooden  framework  is  practically  eliminated. 
A  long  covered  fuselage,  rectangular  in  section  at  the  front  and 
semicircular  at  the  rear,  gradually  tapers  to  a  point,  giving  prac- 
tically a  "stream  line"  form.  This  frame  is  made  of  steel  tubing 


MOXOPLAXES    AXD    BIPLANES 


163 


at  the  front,  but  at  the  rear,,  where  great  strength  is  not  so  neces- 
sary, there  are  some  wooden  crosspieces.  The  motor  is  mounted 
at  the  front  end;  the  planes  are  also  at  the  front;  the  pilot  sits 
back  of  the  planes  with  a  passenger  seat  in  front  of  him,  approxi- 


Courtesy  of  "Flight." 

BATHIAT  FLYING  ON  THE  BREOUET  BIPLANE  AT  ROUEN, 
JUNE,  1910 

mately  over  the  center  of  pressure;  and  at  the  rear  are  carried  the 
rudders. 

Supporting  Planes. — The  framework  of  the  main  planes  con- 
sists essentially  of  two  main  steel  tube  cross  pieces  to  which  are 
fixed  the  numerous  ribs.  The  ribs  are  made  of  a  U-shaped  piece 
of  aluminum  sheeting,  and  are  fastened  to  the  steel  tubes  by  an 


164  MONOPLANES    AND    BIPLANES 

ingenious  elastic  joint.  The  entire  frame  is  covered  with  a  spe- 
cially smoothed  and  oiled  fabric. 

The  section  of  the  planes  is  an  evenly  curved  one,  thick  and 
blunt  at  the  front  and  narrowing  to  a  fine  edge  at  the  rear. 

The  planes  are  not  of  the  same  size,  the  lower  one  being  smaller 
than  the  upper.  They  are,  however,  directly  superimposed,  and 
are  mutually  supported  and  fixed  to  the  framework  by  only  four 
vertical  steel  tube  struts.  The  "box  cell"  arrangement  is  altogether 
absent.  The  planes  are  braced  by  steel  rods  to  the  central  frame, 
and  the  usual  maze  of  cross-wires  is  eliminated.  This  type  of  con- 
struction reduces  the  head  resistance,  and  considerably  increases 
the  lifting  force  for  a  given  horse-power. 

By  reason  of  the  great  elasticity  of  the  planes,  they  give  a  little 
under  pulsations  of  the  wind,  and  transmit  the  disturbing  forces 
of  the  air  waves  to  the  frame,  greatly  diminished.  The  aeroplane 
is  therefore  suspended  elastically  in  its  element,  and  is  in  conse- 
quence assured  of  a  higher  degree  of  stability  and  a  lesser  fatigue 
of  its  parts. 

It  is  possible  because  of  this  elasticity  that,  similar  as  it  is  to 
the  elasticity  of  a  bird's  wing?  the  planes  may  profit  by  the  "internal 
work  of  the  wind/7  and  thus  is  explained,  in  a  measure,  their 
high  lifting  quality. 

The  planes  are  about  7  feet  apart.  The  upper  ones  are  set  at 
a  slight  dihedral  angle.  The  spread  of  the  upper  plane  is  43% 
feet,  the  spread  of  the  lower  plane  32%  feet,  and  their  depth  5% 
feet.  The  total  supporting  surface  is  409  square  feet. 

Elevation  Rudder. — At  the  rear  of  the  machine,  mounted  on  a 
universal  joint  and  held  by  springs,  is  a  cruciform  tail-piece,  the 
horizontal  surface  of  which  serves  as  the  elevation  rudder.  This 
surface  normally  is  "non-lifting,"  and  has  an  area  of  approximately 
25  square  feet.  By  pushing  forward  on  the  steering  column 
mounted  in  front  of  the  pilot,  the  entire  tail  is  turned  down,  thus 
lifting  up  the  rear  of  the  machine,  reducing  the  angle  of  incidence 
of  the  main  surfaces,  and  thereby  causing  the  machine  to  descend. 
By  pulling  this  column  toward  him,  the  aviator  causes  the  machine 
to  ascend. 


MONOPLANES   AND  BIPLANES 


165 


Direction  Rudder. — The  vertical  surface  of  the  tail  serves  as 
the  direction  rudder,  and  is  moved  to  either  side  by  operation  of  the 
steering-wheel  fixed  on  the  control  column. 


\ 


SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION  OF  THE  BREGUET  BIPLANE  "TYPE 

MlLITAIEE  " 


166  MONOPLANES    AND    BIPLANES 

Transverse  Control. — The  transverse  equilibrium  of  the  ma- 
chine is  controlled  by  the  ordinary  system  of  warping.  By  moving 
the  entire  control  column,,  wheel  and  all,  to  the  right,  for  example, 
the  rear  edge  of  the  left  plane  is  turned  down,  thus  increasing  the 
lift  on  that  side. 

Keels. — The  cruciform  tail-piece  not  only  serves  as  a  rudder  for 
both  elevation  and  direction,  but  in  its  normal  position  acts  as  a 
stabilizing  keel  of  great  power.  Due  to  the  springy  character  of 
this  member,  the  stability  is  made  somewhat  automatic.  If  a  sud- 
den gust  should  hit  the  under  side  of  the  tail,  the  machine  would 
tend  to  tilt  up  at  the  rear,  and  therefore  descend.  But  this  same 
gust  would  cause  the  tail  to  be  turned  up  by  an  amount  exactly 
proportional  to  the  strength  of  the  gust.  Since  a  turning  up  of  the 
tail  is  the  movement  for  ascent,  the  tendency  for  the  gust  to  cause 
the  machine  to  descend  will  be  counteracted  in  proportion  to  the 
strength  of  the  gust.  Since,  in  addition,  the  weight  of  this  ma- 
chine is  great,  and  its  momentum  therefore  quite  large,  this  form 
of  stabilizing  device  does  actually  act,  and  very  forcibly  hold,  the 
machine  to  its  course. 

Propulsion. — The  motor  is  placed  at  the  front,  and  drives  the 
propeller  through  reducing  gear.  A  40  to  5&  horse-power  motor  is 
necessary,  the  usual  types  used  being  the  Gnome,  Renault  or  E.  E.  P. 
The  propeller  was  formerly  a  three-bladed  Breguet  metallic  one,  but 
of  late  a  two-bladed  Chauviere  wooden  "Integral"  has  been  used,  al- 
most 9  feet  in  diameter,  6^2  feet  pitch,  and  rotating  at  800  r.p.m. 

Mounting. — The  mounting  is  mainly  on  a  set  of  two  heavy 
rubber-tired  wheels  fitted  on  skids  with  oleo-pneumatic  springs 
under  the  centre  of  gravity,  and  an  extra  heavy  wheel  and  skid  at 
the  front  to  take  very  sudden  landing  shocks  and  protect  the  front 
of  the  frame,  propeller,  etc.  This  wheel  can  be  turned  as  on  an 
automobile. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  of  the  machine  in  flight  varies  from  1,100 
pounds  with  pilot  alone,  up  to  1,800  pounds  with  six  aboard.  The 
speed  is  approximately  53  miles  an  hour.  The  maximum  pounds 
lifted  per  horse-power  are  36,  and  maximum  loading  is  4.4  pounds 


MONOPLANES    AND    BIPLANES  167 

per  square  foot  of  carrying  surface.     The  aspect  ratio  of  the  up- 
per plane  is  7.9  to  1 — an  extremely  high  value. 

There  is  also  a  60  horse-power  "racing  type"  of  Breguet  bi- 
plane, for  which  a  speed  of  62  miles  an  hour  is  claimed.  The 
characteristics  of  this  machine  are:  Spread  of  upper  plane,  40 
feet;  spread  of  lower  plane,  30  feet;  depth,  4%'  feet;  surface  area, 
280  square  feet;  weight,  1,300  to  1,500  pounds;  pounds  per  horse- 
power, 25;  pounds  per  square  foot,  5.4;  and  aspect  ratio  of  7.1  to  1. 

References. — Encycl.  d'Aviation,  v.  2,  No.  14,  p.  98  ;  Flight, 
July  16th,  1910,  p.  553;  December  10th,  1910;  Aero,  October 
26th,  1910;  November  2nd,  1910,  p.  350;  Flugsport,  October 
19th,  1910.  V.  Quittner  and  A.  Vorreiter,  "Neve  Flngzeuge  in 
Paris,"  Zeit.  fur  Fiugtech.  und  Motorluft.,  November  26th, 
1910  ;  Fachzeit.  fur  Flugtechnik,  November  13th,  1910,  p.  15  ;„ 
L'Aerophile,  February  1st,  1910,  p.  58 ;  June  15th,  1910,  p. 
273;  July  loth,  1910,  p.  317;  December  15th,  1910,  p.  558. 

References  on  the  Breffuet-Richet  Helicopters. — L'Aerophile, 
September,  3907,  p.  258;  April  15th,  1909,  p.  175;  La  Nature, 
v.  70,  p.  36,  1907. 

2.   THE  CODY  BIPLANE    (1909) 

Col.  Cody,  an  American,  who  has  for  some  time  resided  in 
England,  distinguished  himself  several  years  ago  as  the  successful 
operator  of  man-lifting  kites.  His  work  in  this  line,  with  regard 
to  army  use  and  scouting,  attracted  much  attention  in  England. 
In  1937,  Col.  Cody  commenced  work  on  a  motor  aeroplane  of  huge 
dimensions.  At  first  the  tests  of  this  machine  were  very  unsuc- 
cessful,, but  with  remarkable  perseverance  Col.  Cody  gradually 
turned  the  failures  into  successes,,  and  finally  in  the  late  summer 
of  1909  he  accomplished  a  superb  flight  of  over  an  hour,  establish- 
ing then  a  cross-country  record  of  the  world.  The  machine  was 
altered  many  times,  and  in  its  final  form  was  the  largest  success- 
ful aeroplane  ever  flown. 

The  Frame. — Bamboo  was  used  extensively  throughout  the 
frame,  but  all  joints  were  carefully  wound  with  steel  wire.  In 
addition  there  were  many  upright  members  of  ash.  At  the  center 
several  members  met  in  the  supporting  chassis  which  was  very 
heavily  built.  Steel  wire  was  used  for  bracing. 

Supporting    Planes. — The    main    planes    were    rectangular    in 


168 


MONOPLANES    AND    BIPLANES 


shape  with  rounded  rear  edges  and  were  identical  and  directly 
superposed.  The  surfaces  were  made  of  canvas  stretched  tightly 
over  wooden  ribs.  At  the  center  the  distance  between  them  was 
9  feet,  but  they  converged  toward  either  end,  and  were  there  sep- 
arated by  only  8  feet.  The'spread  was  52  feet,  the  depth  7.5  feet, 
and  the  area  780  square  feet. 

The  Elevation  Rudder. — At  the   front  of  the  machine,   sup- 
ported by  large  bamboo  outriggers  from  the  central  cell,  were  two 


THE  1909  CODY  BIPLANE  IN  FLIGHT 


equal  surfaces  on  either  side  of  the  center.  These  were  jointly 
movable,  and  served  to  control  the  elevation  of  the  machine.  They 
were  governed  by  the  forward  or  back  motion  of  the  stanchion  upon 
which  the  steering  wheel  was  mounted.  If  the  aviator  wished  to 
rise  he  pulled  the  wheel  towards  him.  This  motion,  by  means  of 
a  lever  system,  caused  the  elevation  rudder  surfaces  to  be  lifted  up^ 
to  the  line  of  flight  and  the  machine  ascended. 

The  Direction  Rudder. — For  steering  to  one  side  or  the  other 
two  surfaces  were  used.     At  the  rear  of  the  machine  was  a  lar^e- 


MONOPLANES    AND    BIPLANES 


1G9 


Side    Elevcr/ion 


170  MONOPLANES    AND    BIPLANES 

vertical  surface,  which  was  the  main  direction  rudder,  while  at  the 
front  was  a  smaller  vertical  surface  used  for  the  same  purpose. 
These  rudders  were  moved  jointly  by  a  cable  and  steering  wheel, 
as  in  automobiles  or  motor  boats.  Their  area  was  about  40  square 
feet. 

Transverse  Control. — Two  balancing  planes  of  30  square  feet 
area,  one  placed  at  either  end  of  the  main  cell,  controlled  the 
transverse  inclination  of  the  machine.  They  were  moved  inversely 
by  cables  leading  from  the  steering  gear  at  command  of  the  aviator. 
If  the  right  end  of  the  machine  were  depressed,  then  the  wing  tip 
on  that  side  was  turned  down,  but  at  the  same  time  the  wing  tip 
on  the  other  end  was  turned  up.  This  caused  not  only  the  de- 
pressed side  to  rise,  but  also  the  raised  side  to  be  depressed,  thus 
righting  the  machine.  When  making  turns  the  machine  could  be 
artificially  inclined  with  this  apparatus.  In  addition  to  the  wing 
tips,  the  transverse  equilibrium  could  be  controlled  by  the  inverse 
movement  of  the  two  halves  of  the  elevation  rudder,  the  one  on  the 
depressed  side  being  elevated  while  the  other  was  turned  down. 

Keels. — There  were  no  keels  in  this  machine,  all  surfaces  serv- 
ing either  to  lift  or  to  direct  the  aeroplane. 

Propulsion. — The  motive  power  was  an  80-horse-power  E.X.Y. 
8-cylinder  motor.  Two  two-bladed  propellers  placed  at  the  front 
of  the  main  cell  were  driven  in  opposite  directions  by  chains  at 
600  r.p.m.  Their  diameter  was  8.25  feet,  and  their  pitch  6  feet. 

The  Seats  for  aviator  and  one  passenger  were  placed  low  at 
the  center  in  front  of  the  main  cell.  The  lower  seat  was  for  the 
aviator,  while  the  other  was  designed  for  the  use  of  an  observer 
in  war  time  to  take  sketches  of  the  enemy's  position,  etc. 

The  Mounting  consisted  of  a  large  pair  of  wheels,  which  carried 
most  of  the  weight,  a  small  wheel  in  front  of  them,  and  a  skid 
in  the  rear.  Wheels  were  also  fixed  on  each  end  of  the  lower  plane 
to  carry  the  machine  easily  over  the  ground  if  it  should  alight  on 
one  end. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  was  from  1,90")  to  2,100  pounds ;  the  speed, 
37  miles  per  hour ;  25  pounds  were  lifted  per  horse-power,  and  2.57 


MONOPLANES    AND   BIPLANES 


171 


pounds  per  square  foot  of  surface.     The  aspect  ratio  was  7  to  1. 

References. — Zeit.  Ver.  Deut.  Ing.,  v.  53,  p.  1143 ;  Aero- 
nautics, v.  4,  pp.  78,  126  ;  v.  5,  pp.  33,  65,  154  ;  Flight,  v.  1, 
pp.  113,  501 ;  Encyl.  d'Av.,  v.  1,  p.  112  ;  Boll.  Soc.  Aer.  Ital., 
v.  6,  p.  288  ;  Vorreiter  A.,  "Motor  Flugapparate"  ;  Sci.  AM., 
v.  101,  p.  198. 

3.   THE    CODY   BIPLANE    (1911) 

Col.  Cody's  newest  biplane,  in  which  he  won  the  British  Miche- 
lin  prize  by  flying  186  miles  at  Farnborough  on  December  31st, 
1910,  greatly  resembles  its  predecessor,  but  is  smaller,  and  dis- 
tinguished by  its  equipment  with  one  propeller  at  the  rear  instead 
of  two  as  formerly.  The  control  system  and  rudders  are  precisely 


Courtesy  of   "Flight." 


MR.  S.    F.    CODY   ON    His    1911    TYPE    BIPLANE,    COMPETING    FOR    THE    BRITISH 
MICHELIN  CUP,  WHICH  HE  WON  BY  A  FLIGHT  OF  186  MILES. 


172 


MONOPLANES    AND    BIPLANES 


SIDE  ELEVATION.  PLAN  AND  FRONT  ELEVATION  OF  THE  CODY    (1911) 


MONOPLANES  .AND   BIPLANES 


173 


the  same  the  balancing  forces  being  distributed  over  different 
parts  of  the  machine,  thus  guarding  against  any  undue  local  stress. 
The  balancers  are  held  normal  by  springs. 

The  Frame. — The  frame  and  skid  construction  is  very  much 
simpler  and  stronger  than  formerly.  Silver  spruce  is  used  in  the 
frame,  bamboo  for  the  outriggers,  and  hickory  for  the  chassis. 

The  Supporting  Planes. — The  two  planes  of  the  main  cell, 
SVo  feet  apart,  have  a  spread  of  46  feet,  a  chord  of  6%  feet,  and 
an  area  of  540  square  feet.  The  depth  of  curvature  is  4  inches, 


Courtesy  of  "Flight/' 

SIDE  VIEW  OF  THE  CODY  (1011) 

and  the  shape  of  the  section  has  a  curious  narrowing  between  the 
spars.    The  surface  is  double  and  made  of  Pegamoid  cloth. 

The  Elevation  Rudder. — The  elevating  surfaces  at  the  front 
have  a  total  area  of  116  square  feet,  a  depth  of  4%  feet,  and  are 
12  feet  in  front  of  the  main  cell.  The  control  is  the  same  as  on 
the  1909  type. 

The  Direction  Rudder. — The  front  direction  rudder  is  elim- 
inated. The  one  at  the  rear  is  retained,  and  has  an  area  of  36 
square  feet. 

Transverse  Control. — Transverse  control  is,  as  on  the  former 
type,  by  means  of  ailerons  and  the  two  halves  of  the  front  rudder. 
The  ailerons  are  each  50  square  feet  in  area. 

Keel. — A  new  departure  is  the  addition  of  a  horizontal  non- 
lifting  keel  at  the  rear. 


174  MONOPLANES   AND   BIPLANES 

Propulsion. — A  63  horse-power  E.  N.  V.  or  Green  motor, 
placed  on  the  lower  plane,  drives  by  chain  a  single  large  wooden- 
bladed  propeller,  10^2  feet  in  diameter  and  10.6  feet  pitch,  at 
600  r.p.m.  This  is  the  largest  propeller  used  on  any  aeroplane 
up  to  the  present. 

A  new  and  smaller  type  with  a  35  horse-power  engine  is  being 
built. 

Speed,  Weight,  Loading  and  Aspect  Ratio. — 

The  speed  of  this  machine  is  about  41  miles  an  hour.  The 
total  weight  is  1,350  to  1,500  pounds;  25  pounds  are  lifted  per 
horse-power,  and  2.8  per  square  foot  of  surface.  The  aspect  ratio 
is  7.1  to  1. 

References. — Flight,  1910,  November  12th,  p.  923;  Novem- 
ber 19th,  p.  945;  Aero,  1910,  October  5th,  p.  276;  October 
12th,  p.  288,  Fachzeit.  fiir  Flugtechnik,  No.  42,  p.  19. 

4.   THE   CURTISS  BIPLANE 

The  Curtiss  biplane,  originated  by  the  Herring-Curtiss  Com- 
pany, embodies  in  its  construction  several  features  that  distin- 
guished the  aeroplanes  built  by  the  Aerial  Experiment  Association, 
of  which  Mr.  Curtiss  was  a  member.  In  June,  1909,  the  first 
flight  of  this  type  was  made.  At  Eheims,  in  August,  this  minia- 
ture biplane,  ably  piloted  by  Mr.  Curtiss,  captured  the  Gordon 
Bennett  Prize  and  Cup  as  well  as  several  others.  It  is  one  of  the 
fastest  biplanes  now  in  use.  Several  machines  of  this  type  are 
being  flown,  notably  by  Messrs.  Curtiss,  Mars,  Hamilton,  Willard, 
McCurdy,  Ely,  Post,  and  Baldwin.  There  is  no  other  type  that 
has  been  as  widely  imitated  by  amateurs  in  this  country  as  the 
Curtiss. 

The  Frame. — The  main  ceil  and  smaller  parts  are  made  of 
ash  and  spruce,  and  the  large  outriggers,  of  bamboo.  Several  mem- 
bers of  the  frame  meet  at  the  front  wheel.  Small  cables  as  well 
as  wires  are  used  for  bracing. 

The  Supporting  Planes. — The  main  carrying  planes  are  of  very 
finished  construction.  They  consist  of  two  identical  directly  super- 
posed surfaces  made  of  one  or  two  layers  of  Baldwin  rubber  silk, 


MONOPLANES    AND   BIPLANES 


175 


tacked  to  spruce  ribs  and  laced  to  the  frame.  A  distance  of  5  feet 
separates  the  surfaces.  Their  spread  is  26.42  feet,  the  depth  4.5 
feet,  and  the  area  223  square  feet. 

The  Elevation  Rudder. — The  elevation  rudder  is  a  small  bi- 
plane cell  consisting  of  two  identical  surfaces,  24  square  feet  in 
area,  mounted  at  the  front  on  bamboo  outriggers.  It  is  governed 
by  a  long  bamboo  rod  attached  to  the  stanchion  on  which  the  steer- 
ing wheel  is  mounted.  By  pushing  out  on  this,  the  rudder  is 
turned  down  and  the  machine  descends.  By  pulling  in,  the  ma- 
chine is  caused  to  ascend. 


THE   Cui 


WHICH  WON  THE   INTERNATIONAL  CUP  AT   UIIEIMS 
AUGUST,  1909 


The  Direction  Rudder. — The  rudder  for  steering  from  right 
to  left  consists  of  a  single  vertical  surface  placed  in  the  rear  and 
operated  by  the  steering  wheel  and  cables,  which  are  run  inside 
the  bamboo  outrigger.  Its  area  is  6.6  square  feet. 

Transverse  Control. — -Two  balancing  planes  of  12  square  feet 
area  each,  one  placed  at  either  end  of  the  main  cell,  are  used  to 
preserve  lateral  balance.  They  are  tipped  inversely  by  means  of 
a  brace  fitted  to  and  swayed  by  the  aviator's  body.  If  the  machine 
is  depressed  on  the  left  side,  the  aviator  leans  toward  the  right, 
and  in  so  doing  moves  the  brace,  causing  the  wing  tip  on  the 


176 


MONOPLANES    AND    BIPLANES 


left  side  to  be  turned  down  and  the  one  on  the  right  to  be  turned 
up,  thus  righting  the  machine.  By  "turning  down"  is  here  meant 
a  motion  relative  to  the  axis  of  the  wing  tip  itself  and  not  to  the 
line  of  flight.  When  a  wing  tip  of  this  sort  is  turned  down,  its 
incidence,  i.  e.,  the  angle  it  makes  with  the  line  of  flight,  is  posi- 
tive and  it  therefore  exerts  a  greater  lifting  force. 


GLEN  CURTISS  AFTER  His  ALBANY-NEW  YORK  FLIGHT 

When  making  a  turn  to  the  right,  for  example,  the  aviator, 
by  leaning  to  the  right,  and  thus  causing  the  left  end  to  lift  up, 
can  make  a  sharper  turn  than  by  use  of  the  direction  rudder  alone. 

Keels. — A  horizontal  fixed  surface  is  placed  in  the  rear  and 
steadies  the  machine  greatly.  Its  area  is  15  square  feet.  A  small 
triangular  vertical  surface  is  sometimes  placed  in  front. 

Propulsion. — A    25    horse-power,    4-cylinder    Curtiss    motor, 


MONOPLANES    AND    BIPLANES 


177 


placed  well  up  between  the  two  surfaces  at  the  rear,  drives  direct 
a  two-bladed  wooden  propeller  at  1.200  r.p.m.  The  propeller  has  a 
pitch  of  5  feet  and  a  diameter  of  6  feet. 


Elevation 


<3co/e     of   feel 


P-roni    £.  levcffion. 
PLAN  AND  ELEVATIONS  OF  THE  CURTISS  BIPLANE 


178 


MONOPLANES    AND    BIPLANES 


The  Seat  for  the  aviator  is  on  the  framing  in  front  of  the  main 
cell  and  in  line  with  the  motor.  When  a  passenger  is  carried  a 
seat  is  provided  to  the  side  and  somewhat  below  the  aviator. 

The  Mounting  is  on  three  rubber-tired  wheels,  rigidly  fixed 
to  the  frame,  no  springs  being  provided. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  530  to  570  pounds,  and  the  speed 
is  47  m.p.h. ;  22  pounds  are  lifted  per  horse-power  and  2.5  pounds 
per  square  foot  of  surface.  The  aspect  ratio  is  5.65  to  1. 


A  NEAR  FRONT  VIEW  or  A  CCRTISS  BIPLANE 

Recent  Alterations. — Mr.  Willard  has  recently  flown  a  larger 
type  of  Curtiss  biplane,  in  which  he  has  succeeded  in  carrying  three 
passengers  besides  himself. 

This  machine  is  precisely  of  the  same  general  design  as  the 
regular  Curtiss  type,  but  differs  from  it  in  size. 

The  supporting  planes  have  a  spread  of  32  feet,  a  depth  of 
5  feet,  and  an  area  of  316  square  feet.  The  elevation  rudder  is 
31  square  feet  in  area,  and  the  direction  rudder  7.5  square  feet 
in  area.  The  rear  horizontal  keel  has  an  area  of  17.5  square  ieet, 
while  the  ailerons  are  each  ?-7  square  feet  in  size.  A  Curtiss  8- 


MONOPLANES   AND    BIPLANES  179 

cylinder  59  horse-power  motor  is  used  and  drives  direct  a  7-foot 
propeller  at  1,100  r.p.m.  The  maximum  total  weight  in  flight 
is  1,150  pounds.  22.6  pounds  are  carried  per  horse-power,  and 
3.64  pounds  per  square  foot  of  surface.  The  aspect  ratio  is  6.4 
to  1. 

In  most  of  the  latest  Curtiss  machines,  a  single  plane  eleva- 
tion rudder  is  used,  and  the  side  ailerons  are  replaced  by  four  flaps 
on  the  trailing  edges  of  the  planes,  or  are  placed  on  either  side 
at  the  rear  of  the  cell. 

In  the  new  machine  used  by  Mr.  Curtiss  in  his  recent  inter- 
esting experiments  over  water,  the  single  plane  elevation  rudder 
is  aided  in  its  action  by  movable  flaps  on  the  rear  of  the  horizon- 
tal keel  at  the  back,  a  disposition  similar  to  that  used  on  the  Far- 
man  biplanes.  The  fan  shape  of  this  rear  keel  as  on  Mr.  Ely's 
machine  is  also  a  new  departure. 

References. — Aeronautics,  v.  5,  p.  13,  86.  137 ;  Am.  Aero- 
naut, v.  1,  p.  1  (new  series)  ;  Boll.  Soc.  Aer.  Ital.,  v.  6,  p. 
286 ;  Sci.  AMERICAN,  v.  100,  p.  460 ;  Encycl.  d'Av.,  v.  1,  p. 
24  ;  Am.  Machinist,  v.  32,  p.  49 ;  Flight,  v.  1,  p.  389  ;  Zeit. 
fur  Luft.,  v.  13,  p.  816;  Aerophile,  v.  17,  p.  488;  Locomocion 
Aerea,  v.  1,  p.  78  ;  Genie  Civil,  v.  55,  p.  343. 

5.     THE  DUFAUX  BIPLANE 

This  biplane,  built  in  Switzerland  by  the  Dufaux  Brothers, 
is  one  of  the  most  successful  types  of  biplanes  equipped  with 
a  tractor  screw.  It  is  noteworthy  for  its  light  weight.  Excepting 
the  main  surfaces,  the  Dufaux  resembles  the  Antoinette  more  than 
any  other  type,  and  possesses  some  of  the  gracefulness  that  is  so 
characteristic  of  that  monoplane.  Many  excellent  flights  have  been 
made  by  this  machine,  among  them  a  36-kilometer  flight  on  July 
12th,  1910.  Toward  the  end  of  August,  the  Dufaux  biplane  was 
flown  across  the  Lake  of  Geneva,  a  distance  of  41  miles,  with  per- 
fect ease  and  at  high  speed. 

As  early  as  October,  1905,  the  Dufaux  Brothers  were  experi- 
menting with  heavier-than-air  machines.  At  this  date  they  had 
built  a  very  light  engine  and  applied  it  to  a  helicopter.  This  appa- 
ratus succeeded  in  lifting  54  pounds. 

In  the  summer  of  1908,  an  interesting  triplane  was  built  by 


180 


MONOPLANES    AND   BIPLANES 


them,  650  square  feet  in  area  and  equipped  with  a  125  horse-power 
eight-cylinder  motor.    The  total  weight  was  1,400  pounds. 

The  Frame. — The  long  central  frame  or  fuselage  of  the  Dufaux 
is  similar  to  that  of  a  monoplane,  and  the  latticed  framework 
itself  reminds  one  strongly  of  the  Antoinette.  The  disposition  of 


0 Jcaf  mfxt  10 


THE  DUFAUX  BIPLANE,  SIDE  ELEVATION,  PLAN  AND  FRONT  ELEVATION 


MONOPLANES    AND    BIPLANES  181 

parts  is  exactly  as  on  the  ordinary  monoplane,  the  motor  and  pro- 
peller being  at  the  front,  the  rudders  and  keels  at  the  rear,  and 
the  seat  just  back  of  the  main  planes. 

The  Supporting  Planes. — The  main  planes  are  similar  and 
directly  superposed.  They  are  constructed  of  the  usual  wooden 
framework  covered  above  and  below  with  rubber  fabric.  The  two 
halves  of  the  main  cell  are  set  at  a  slight  dihedral  angle.  Their 
curvature  is  quite  flat  and  narrow.  The  spread  is  28  feet,  the  depth 
5  feet,  and  the  area  260  square  feet. 

Elevation  Rudder. — The  elevation  rudder  consists  of  a  single 
horizontal  surface  at  the  rear,  triangular  in  shape,  and  operated 
by  a  wheel  at  the  aviator's  right  hand,  exactly  as  on  the  An- 
toinette. 

Direction  Rudder. — The  direction  rudder  consists  of  two  trian- 
gular surfaces  at  the  rear,  similar  to  those  on  the  Antoinette,  but 
smaller.  The  direction  is  controlled  by  a  foot  pedal,  which  is 
turned  to  the  right  or  left,  according  as  the  desired  turn  is  to  right 
or  left. 

Transverse  Control. — The  transverse  control  is  effected  by  the 
use  of  ailerons,  one  pivoted  at  the  rear  of  the  main  cell  on  either 
side  and  midway  between  the  planes.  The  ailerons  are  operated 
by  a  lever  in  the  aviator's  left  hand.  By  pulling  the  lever  to  the 
right,  for  example,  the  left  aileron  is  turned  down,  thus  increasing 
the  lift  on  the  left  side. 

Keels. — A  vertical  keel  and  a  horizontal  keel  or  empennage, 
both  of  which  terminate  in  their  respective  rudders,  are  provided 
and  greatly  resemble  the  Antoinette. 

Propulsion. — An  eight-cylinder  E.  N.  V.  50  horse-power  motor 
is  mounted  at  the  front,  The  propeller  is  driven  direct  at  1.300 
r.p.m.,  and  is  7  feet  in  diameter.  A  radiator  is  placed  back  of  the 
motor. 

Mounting. — The  mounting  is  essentially  on  two  wheels  fitted 
with  springs  on  a  steel  tube  chassis  (a  la  Bleriot)  with  a  single 
skid  projecting  out  in  front  at  the  center,  similar  to  the  An- 
toinette. There  is  also  a  small  skid  at  the  rear. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 


182  MONOPLANES    AND    BIPLANES 

The  total  weight  in  flight  is  about  550  pounds;  11  pounds  are 
lifted  per  horse-power;  and  2.1  pounds  are  carried  per  square  foot 
of  surface.  The  aspect  ratio  is  5.6  to  1. 

References. — L'Aerophile,       January     15th,     1910,     p.     31 ; 
October  1st,  1910;  Flight,  August  27th,   1910,  p.  696. 

6.    THE  DUNNE  BIPLANE 

The  Dunne  biplane,  constructed  in  England  by  Short  Brothers 
to  the  design  of  Lieut.  J.  W.  Dunne,  is  very  solidly  built  and  pre- 
sents a  very  unusual  appearance.  In  the  numerous  nights  that 
have  been  made  at  East-church,  Isle  of  Sheppey,  exceptional  sta- 
bility was  exhibited  by  this  biplane,  and  since  its  outstanding  fea- 
tures are  the  absence  of  the  usual  elevation  and  direction  rudders, 
and  the  curious  shape  of  the  main  cell,  it  has  excited. much  inter- 
est and  comment. 

It  is  said  that  the  British  army  experimented  with  a  proto- 
type of  this  machine,  in  secret,  some  years  ago. 

The  Frame. — The  construction  of  the  main  cell  is  of  the  usual 
wooden  and  wire  frame,  canvas-covered  type.  At  the  centre  there 
is  built  in  a  skiff-like  body  18  feet  long  containing  the  motor, 
seat,  controlling  levers,  radiator,  etc. 

The  Supporting  Planes. — The  conspicuous  feature  of  this  ma- 
chine is  the  employment  of  the  dihedral  principle,  laterally,  trans- 
versely, and  longitudinally. 

The  general  aspect  of  the  main  planes  are  evident  from  the 
accompanying  scale  diagrams. 

The  greatest  fore  and  aft  direction  is  constituted  by  the  wings 
themselves. 

The  incidence  of  the  tips  is  much  less  than  the  incidence  at 
the  center.  In  flight  the  angle  is  very  low  indeed,  and  is  certainly 
negative  at  the  ends.  The  camber  of  the  ribs  is  a  very  interesting 
feature.  At  the  center  the  ribs  have  their  greatest  depth 
of  camber  far  to  the  front,  with  a  long  straight  portion  to 
the  rear.  But  at  the  ends  the  ribs  are  curved  so  that  the  greatest 
depth  of  camber  is  about  at  the  center.  The  theory  involved  in 
this  type  of  construction  is  very  interesting,  and  indicates  that  by 


MONOPLANES    AND   BIPLANES  183 

making  use  of  the  variations  in  position  of  the  center  of  pressure 
a  semi-automatic  balance  is  obtained. 

The  planes  are  6  feet  apart,  6  feet  in  depth,  and  spread  20 
feet  4.1/2  inches  longitudinally  and  46  feet  laterally.  The  total 
area  is  527  square  feet. 

Elevation. — At  the  rear  ends  of  each  plane  are  hinged  flaps, 
each  ~y2  feet  wide  and  12i/>  square  feet  in  area,  controlled  by  a 
left-hand  and  a  right-hand  lever.  They  are  so  connected  that 
when  the  right-hand  lever  is  pulled  back,  and  the  left-hand  lever  is 


Courtesy  of   "Flight." 

A  REAR  THREE-QUARTER  VIEW  OF  THE  DUNNE  BIPLANE 

This   photograph  is  worthy  of  study  because  it  gives  the  correct  impression  of 
the   shape,   and    slope   of  the   main   planes. 

pushed  forward,  then  the  left  ailerons  are  pulled  down,  lifting  up 
that  side  and  the  right  ones  are  turned  up.  When  both  levers  are 
pulled  back  together,  both  flaps  are  turned  up,  and  since  they  are 
to  the  rear  of  the  center  of  support,  the  entire  machine  will  be 
turned  up  for  ascent. 

Direction. — When  steering  to  the  right,  for  example,  the  right 
lever  is  drawn  back  and  the  left  pushed  forward,  thus  pulling  up 
the  right  flap  and  pulling  down  the  left. 

The  angle  of  incidence  of  the  ends  is  always  negative.  There- 
fore turning  up  the  right  flap  increases  still  further  the  nega- 
tive incident  angle,  and  consequently  greatly  increases  the  negative 
drift,  thus  causing  the  right  side  of  the  machine  to  slow  down,  at 
the  same  time  as  it  is  depressed.  But  since  the  flaps  are  at  the 


184 


MONOPLANES    AND    BIPLANES 


THE  DUNNE  BIPLANE.     PLAN  AND  ELEVATIONS 


MOXOPLAXE8    AXD    BIPLAXES  185 

rear  of  the  center  of  gravity,  and  since  turning  up  the  right  flaps 
causes  this  end  to  sink  (like  the  tail  of  a  Bleriot,  for  example), 
there  is  a  tendency  for  the  entire  machine  to  ascend.  To  counter- 
act this,  the  left  lever  is  pushed  over,  thus  increasing  the  lift  on 
this  end  and  decreasing  the  negative  incident  angle.  This  now 
results  in  a  decrease  of  drift  on  this  side,  and  causes  the  machine 
to  "skew"  around  faster  and  to  "bank"  with  the  right  down  and 
the  left  up. 

Transverse  Control. — The  character  of  the  planes  on  this  bi- 
plane give  it  practically  an  automatic  transverse  equilibrium,  so 
that  there  is  no  distinct  and  separate  manner  of  controlling  the 
lateral  inclination  of  the  machine.  The  manner  in  which  this 
aeroplane  is  artificially  inclined  when  making  turns,  however,  has 
already  been  described. 

Keels. — The  end  panels  of  the  main  cell  are  covered-in,  giv- 
ing a  vertical  keel  at  each  side,  which  aids  materially  in  the  vari- 
ous movements  for  equilibrium  and  holds  the  machine  to  its  course, 
preventing  any  skidding  sideways,  etc. 

Propulsion.— Two  wooden  propellers  are  mounted  on  a  frame 
built  out  on  either  side  of  the  central  body.  These  propellers  are 
7  feet  in  diameter,  7%  feet  pitch,  and  rotate  at  669  r.p.m.  They 
are  driven  by  chains  from  a  50  horse-power  four-cylinder  Green 
engine,  and  are  rotated  in  the  same  direction.  To  counteract  the 
torque  resulting  from  this,  a  weight  is  fixed  on  one  end  of  the 
machine.  This  is  not  a  very  good  provision. 

Mounting. — The  mounting  is  similar  to  the  old  Voisin  type, 
and  consists  of  two  rubber-tired  wheels  mounted  on  a  steel-tube 
chassis  fitted  with  coiled  steel  springs  at  the  front  and  a  single 
wheel  and  skid  at  the  rear. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  in  flight  is  about  1,700  pounds,  34  pounds 
are  lifted  per  horse-power,  and  3.2  per  square  foot  of  surface. 
The  aspect  ratio,  considering  the  actual  width  of  the  planes,  is 
9  to  1,  and  considering  the  projected  span  of  46  feet,  is  7.6  to  1. 

References. — Flight,    June   4th,    1910;    June    18th,    1910,    p. 
459;  June  25th,  1910;  Flugsport,  July,   1910. 


186 


MONOPLANES   AND   BIPLANES 


MONOPLANES    AND    BIPLANES  187 

7.    THE    FARM  AN   BIPLANE    (1909) 

Henri  Farman,  in  1907,  began  his  career  as  an  aviator  by 
making  short  nights  of  a  few  seconds  duration  on  a  biplane  con- 
structed for  him  by  the  Voisin  brothers.  On  January  13th,  1908,, 
he  succeeded  in  flying  one  kilometer  in  a  closed  circuit,  thereby 
winning  the  Deutsch-Archdeacon  prize,  the  first  great  prize  offered 
for  an  aeroplane  flight.  Until  the  end  of  that  year  Farman  flew 
this  machine  and  with  it  conducted  a  series  of  experiments  on 
stability.  In  the  early  part  of  1909,  having  severed  his  connection 
with  the  Voisins,  Farman  opened  an  aeroplane  factory  at  Chalons, 
France,  and  began  manufacturing  aeroplanes  himself.  His  design 
was  original  in  many  ways,  and  embodied  several  practical  inno- 
vations that  his  previous  experience  had  suggested. 

The  Farman  biplane  has  been  used  extensively  in  Europe,  and 
notably  by  the  well-known  aviators  Paulhan,  Weyman,  White, 
etc.  More  than  one  hundred  of  this  type  are  in  use  or  under 
construction,  and  for  a  slow  but  trustworthy  machine  it  has  been 
found  very  satisfactory. 

The  Frame. — The  frame  consists  essentially  of  a  main  box  cell, 
somewhat  similar  in  design  to  a  Pratt  truss,  counterbraced 
throughout,  with  identical  upper  and  lower  chords,  uprights  of 
wood  acting  as  compression  members  and  cross  wires  as  tension 
members.  The  supporting  planes  are  analogous  to  the  upper  and 
lower  decks  of  such  a  truss. 

The  Supporting  Planes. — There  are  two  main  carrying  sur- 
faces, identical  and  directly  superposed.  Their,  sectional  curvature 
is  of  the  cambered  shape,  used  so  generally  in  present  day  aero- 
planes. The  curvature  is  concave  on  the  under  side,  and  of  para- 
bolic character.  The  surfaces  are  made  of  " Continental"  cloth, 
a  special  rubber  fabric,'  stretched  tightly  over  ash  ribs.  The  spread 
of  the  surfaces  is  33  feet;  the  depth,  6.6  feet,  and  the  total  area, 
430  square  feet.  The  distance  between  planes  is  7  feet. 

The  Elevation  Rudder. — The  elevation  rudder  originally  con- 
sisted of  a  single  surface,  about  43  square  feet  in  area  situated 
well  out  in  front.  It  was  hinged  and  braced  to  two  sets  of  out- 
riggers, firmly  attached  to  the  main  cell,  and  was  controlled  by 


188 


MONOPLANES    AND    BIPLANES 


a  large  lever  in  the  aviator's  right  hand.  By  pulling  in  on  this 
lever,  the  rudder  was  tilted  up  and  the  machine  was  caused  to 
rise.  By  pushing  out  on  the  lever,  the  rudder  was  dipped  down 
and  the  machine  was  caused  to  descend.  This  method  of  control 
is  almost  instinctive  and  very  easy  to  acquire.  On  the  more  recent 
types  this  front  rudder  is  reduced  in  size  and  in  addition  the  rear 
flap  of  the  upper  keel  at  the  stern  is  moved  jointly  with  it. 


GRAHAME-WHITE  ON  His  FARUAX  AT  BELMONT  PARK 

The  rudders  and  ailerons  are  all  in  their  normal  positions.  The  bulletin  board 
indicates  that  he  has  just  completed  19  laps  in  an  hourly  distance  event. 
Note  the  hangars  and  tents  in  the  distance. 

The  Direction  Rudder. — Two  equal  vertically  placed  surfaces 
in  the  extreme  rear  serve  as  the  direction  rudder.  They  are  moved 
jointry  and  have  an  area  of  approximately  30  square  feet.  A 
foot  lever,  hinged  at  its  center,  is  so  connected  to  these  rudders 
by  cables  that  when  the  aviator  pressing  on  this  lever  with  his 
feet  turns  it,  for  example,  to  the  left,  then  the  machine  will  turn 
to  the  left. 

Transverse  Control. — The  control  of  the  lateral  equilibrium 
i.  e.,  the  tipping  from  side  to  side,  is  effected  by  the  use  of  "wing 


MONOPLANES    AND    BIPLANES 


189 


tips,"  four  flaps  constituting  the  rear  ends  of  each  plane.  A  lever 
in  the  aviator's  right  hand  (the  same  one  as  used  to  operate  the 
elevation  rudder)  can  be  moved  from  side  to  side.  It  is  connected 
by  wires  to  the  lower  flap  on  either  side.  These  flaps  in  turn 
transmit  the  movement  imparted  to  them  by  the  lever  to  the  flaps 


Scale     of   feel 


ELEVATION  AND  PLAN  OF  THE  FAKMAN  BIPLANE  WITH  WHICH  HENRI  FAR- 
MAN   WON   THE  MlCHELIN    PRIZE    IN   1909 


190 


MONOPLANES    AND    BiPf.AXES 


directly  above  them  by  means  of  a  further  wire  connection.  When 
the  machine  is  standing  still  the  flaps  merely  hang  down  loosely 
and  the  wires  relax.  But  as  soon  as  the  machine  takes  to  flight 
the  flaps  fly  out,,  very  much  like  a  flag  blown  by  the  breeze,  and 
in  this  position  the  connecting  wires  are  extended  their  full  length, 
and  the  lever  is  in  control. 

If,  for  example,  the  machine  should  tip  suddenly  down  on  the 
aviator's  right  side  then  the  lever  is  promptly  moved  over  to  the 
left.  This  action  causes  the  flaps  on  the  right  end  of  the  machine 
to  be  pulled  down,  and  since  this  involves  an  increased  angle 


FRONT  ELEVATION  OF  THE  FARMAN  BIPLANE 

of  incidence  of  the  flaps,  the  lift  they  exert  is  increased.  This 
is  sufficient  to  bring  the  machine  back  to  an  even  keel.  During 
this  process  the  wires  leading  to  the  flaps  on  the  other  end  have 
been  relaxed,  since  both  sets  of  connecting  wires  are  taut  only 
when  the  lever  is  in  mid-position.  The  flaps  on  the  opposite  end, 
therefore,  have  in  no  way  been  affected,  except  to  be  able  to  fly  out 

more  freelv  in  the  wind  stream. 

•  * 

When  making  turns,  in  addition  to  using  the  direction  rudder, 
the  machine  is  often  artificially  inclined  by  the  use  of  the  trans- 
verse control.  When  turning  to  the  right,  for  example,  an  in- 
stant before  setting  the  direction  rudder  the  lever  is  moved  over 
to  the  right  side.  This  lifts  up  the  left  end  of  the  machine  and 
therefore  causes  the  turn  to  be  sharper. 

Keels. — Two  horizontal  surfaces  at  the  rear,  of  approximately 
80  square  feet  area,  act  as  keels.  Their  angle  of  incidence  is  low, 


MONOPLANES    AXD   BIPLANES 


391 


and  the  lift  they  exert  is  s?mall,  their  only  function  being  to  steady 
the  machine  longitudinally. 


THE  GNOME  ENGINE  PROPELLER  AND  FUEL  TANK  OF 
PAULHAN'S  FARMAN  BIPLANE 

Note  the  rubber  band  spring  between  the  skid  and  axle 

of  wheels. 


Propulsion. — A  50  horse-power  7-cylinder,  Gnome  rotary,  air- 
cooled  motor  is  mounted  on  a  shaft  in  the  rear  of  the  lower  plane. 
A  two-bladed  Chauviere  wooden  propeller  is  directly  connected 
to  this  motor  and  rotates  with  it  at  1,200  r.p.m.  The  pitch  of  the 
propeller  is  4.62  feet  and  its  diameter  is  8.5  feet. 


19-3 


MONOPLAN  KS    A  X  I)  .  B I  I'  LA  X  KS 


X     * 

<    1 

*4         C5 


MONOPLANES    AND    BIPLANES  193 

The  Seats  for  aviator  and  two  passengers  are  placed  on  the 
front  of  the  lower  plane. 

The  Mounting,  or  apparatus  upon  which  the  machine  starts 
and  alights,  consists  of  two  long  skids  forming  part  of  the  frame- 
work, upon  each  of  which  is  mounted  a  pair  of  wheels.  When 
starting,  this  machine  runs  along  the  ground  on  its  wheels,  but 
when  alighting,  the  wheels,  which  are  attached  to  rubber  springs, 
give  way,  and  the  machine  lands  on  its  skids. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  varies  greatly  with  the  amount  of  gasoline 
taken  aboard,  the  number  of  passengers,  etc.  The  limits  within 
which  this  value  lies,  however,  are  given  and  all  calculations  are 
made  for  an  approximate  mean  weight  of  the  machine  with  aviator 
aboard  ready  for  flight.  The  weight  of  the  Farman  machine  is 
from  1,100  pounds  to  1.3.50  pounds;  the  speed,  37  miles  per  hour; 
24  pounds  are  lifted  per  horse-power  and  2.8  pounds  per  square 
foot  of  surface.  The  aspect  ratio  is  5  to  1. 

Recent  Alterations. — Some  of  the  more  recent  types  of  Farman 
machines  are  fitted  with  a  single  surface  direction  rudder,  instead 
of  the  twin  surfaces.  The  elevation  rudder,  in  front,  is  made 
smaller,  and  in  addition  the  rear  end  of  the  upper  of  the  two 
fixed  horizontal  keels  (at  the  rear  of  the  machine)  is  made  mov- 
able conjointly  with  the  front  rudder  to  control  the  elevation  of 
the  machine  as  already  noted.  In  some  of  the  machines  only  one 
surface  is  used  at  the  rear. 

The  two  small  wheels  supporting  the  rear  cell  are  replaced  by 
a  single  skid.  Other  characteristics  are  substantially  as  given. 

The  new  racing  type  of  Farman  has  the  following  character- 
istics :  The  surface  is  reduced  to  350  square  feet,  and  the  spread 
to  28  feet.  The  total  weight  in  flight  is  about  1.050  pounds. 
Twenty-one  pounds  are  lifted  per  horse-power,  and  3.0  pounds  per 
square  foot  of  surface.  The  aspect  ratio  is  4.2  to  1 . 

References. — Aerophile,  v.  17.  p.  220.  p.  488;  Aeronautics, 
v.  4,  p.  206  ;  v.  5,  p.  218  :  Flight,  v.  1,  p.  641  ;  Flug  Motor 
Tech..  No.  22.  p.  10:  Boll.  T,oc.  Aer.  Italiano,  v.  6.  p.  288; 
Lo^omocion  Aeren.  v  1,  p.  78;  Aeronautics  (Brit.),  v.  2, 
p.  117  ;  Sci.  AM.  SUP.,  v.  68,  p.  324  ;  La  Nature,  v.  37,  p.  329. 


394  MONOPLANES    AND   BIPLANES 

8.  THE  "FARM AN  MILITAIRE"  BIPLANE   (TYPE  MICHELIN) 

Henri  Farman  on  this  machine  established  the  world's  record 
for  duration  of  flight,  when  on  December  18th,  1910,  he  flew  con- 
tinuously for  almost  eight  hours  and  a  half.  This  wonderful 


HENIII   FARMAN  ON   THE   -TYPE   MICHELIN,"    WITH  WHICH   HE   ESTABLISHED  A 

DURATION  RECORD  OF  8h.  AND  28m.  ON  DEC.  18,  1910,  COVERING  288  MILES. 

Note  the  enclosed  body  and  huge  fuel  tanks. 

achievement  was  really  made  possible  by  the  great  weight-lifting 
capacity  of  this  type,  enabling  him  to  carry  almost  450 
pounds  of  fuel  in  an  enormous  tank.  The  "type  militaire"  ia 
remarkable  for  its  great  size,  the  newly  adopted  inclosed  body,  the 
dihedral  angle  of  the  planes,  and  its  three  direction  rudders.  This 
type  is  very  steady,  slow,  and  capable  of  making  trips  that  it  would 


MONOPLANES    AND    BIPLANES  195 

tax  many  an  automobile  to  make,  and  that  in  fact  few  trains  can 
accomplish.    A  slightly  smaller  type  has  attained  great  success. 

Weyman  made  his  flight  from  Paris  to  Clermont,  420  kilo- 
meters, in  seven  hours,  on  a  biplane  of  this  type.  Wynmalen  made 
the  round  trip  between  Paris  and  Brussels  with  a  .passenger  far 
quicker  than  the  fastest  express  train,  and  in  many  ways  with 
greater  security. 

Height  records,  distance  records,  five-passenger-carrying  records, 
and  a  great  variety  of  special  prizes  have  been  made  and  won  by 
this  type  and  types  similar  to  it.  The  slow  speed  does  not  at  all 
indicate  that  the  type  is  inefficient,  but  on  the  contrary,  makes  it 
far  safer  and  far  more  serviceable,  especially  in  military  work, 
where  hovering  over  one  spot  is  of  great  importance. 

Almost  unlimited  are  the  possibilities  of  practical  utilization 
in  commerce,  in  war,  and  in  recreation,  of  a  type  of  this  character, 
capable  of  flying  from  sunrise  to  sunset  without  ever  touching 
terra  firma. 

The  Frame. — The  details  of  the  framework  and  the  general 
character  of  the  main  cell,  outriggers,  rear  cell,  etc.,  are  similar 
to  the  other  Farm  an  types;  steel  tubing,  however  is  more  generally 
used.  A  new  departure  is  the  introduction  of  a  covered  central 
body,  containing  the  seats,  the  tanks,  etc.,  and  shaped  to  a  stream 
line  form,  very  much  as  on  the  Maurice  Farman.  The  outer 
panels  of  the  upper  plane  are  hinged  and  held  in  place  by  an  in- 
clined movable  steel  tube  strut  enabling  these  parts  to  be  folded 
down  when  not  in  use.  This  disposition  was  first  installed  on  the 
smaller  Farman  of  Fischer. 

TJie  Supporting  Planes. — As  on  many  of  the  Farman  biplanes 
of  1910,  the  lower  plane  is  made  shorter  than  the  upper.  The 
spread  on  the  upper  plane  is  491/4  feet  and  that  of  the  lower  30 
feet.  The  total  area  is  540  square  feet,  which  makes  this  the  same 
size  as  the  Cody. 

The  entering  edge  of  the  upper  plane  is  horizontal,  but  the 
trailing  edge  is  curved  up  from  the  center,  thus  giving  to  the 
upper  plane  an  incident  angle  which  gradually  decreases  from  the 
center  to  the  ends.  This  is  supposed  to  increase  stability  and 


196 


MONOPLANES    AND    BIPLANES 


lift.     The  entire  lower  surface  is  set  at  a  dihedral  angle  which 
is  rather  large. 

The    Control    System. — The    rudders    and    controlling    system 
are  the  same  as  on  the  other  type — a  front  elevation  rudder  com- 


PLAN  OF  THE  H.  FARMAN  "TYPE  MICHELIN  " 
Compare  with   tho   Wright  Model   K,   drawn   to   the   same   scale. 


MONOPLANES    AND    BIPLANES 


197 


bined  with  the  movable  trailing  flap  on  the  upper  surface  of  the 
rear  cell,  and  ailerons  on  the  outer  ends  of  the  upper  main  surface. 
Three  direction  rudders  instead  of  two  are  installed. 


Some  of  the  earlier  "types  militaires"  were  equipped  with  an 
aileron  on  each  end  of  the  lower  panel  and  two  above,  making 
six  in  all. 


L98 


MONOPLANES    AND    BIPLANES 


The  motion  power  is  the  usual  seven-cylinder  50  horse-power 
Gnome  plant,  with  an  Eole  propeller. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 
The  total  weight  is  from  1,300  to  1,850  pounds.     The  speed 
is  about  341/2  miles  an  hour;  37  pounds  are  lifted  per  horse-power, 


»V»:  *tt 


FRONT  VIEW  or  THE  "TYPE  MICHELIN  " 

and  3.4  pounds  per  square  foot  of.  surface.     The  aspect  ratio  is  6.8 
to  1. 

References. — Scr.   AM..   Itecember  31st,    1010.  p.   516;  Aero, 
December  7th,  1910,  p.  451  ;  December  14th,  1910. 

9.      THE  MAURICE  FARMAN   BIPLANE 

Early  in  1909  Maurice  Farman,  a  brother  of  the  pioneer,  Henri 
Farman,  began  his  career  as  an  aeroplane  constructor,  rivaling  in 
due  time  his  brother.  Although  up  to  the  late  summer  of  1910 
they  conducted  their  business  separately,  the  Farman  brothel's 
are  now  working  in  partnership,  the  H.  Farman  and  the  M.  Far- 
man being  two  types  made  by  the  same  firm. 

The  first  M.  Farman  biplane  was  constructed  by  M.  Mallet  and 
tried  at  Buc  in  January,  1909.  In  this  machine  the  planes  were 
warped,  although  the  general  aspect  was  the  same.  Since  then  thia 
type  has  been  greatly  refined.  It  is  to-day  an  excellent  and  well- 


MONOPLANES    AND    BIPLANES 


199 


built  machine,  and  ha<  attained  conspicuous  success.  M.  Farman 
has  made  many  notable  nights  with  this  machine.  Among  the 
other  pilots  are  Lieut.  Byasson,  who  flew  from  Paris  to  Chartres 
and  back,  the  last  week  in  October,  1910.  Capt.  Eteve  and  Lieut.  Lu- 
cas, former  Wright  pupils,  are  now  flying  this  type.  Only  recently, 


THE  MAURICE  FARMAX  BIPLANE 
Tabuteau  Winning  the  1910  Michelin  Prize. 


in  the  first  week  of  November  last,  Maurice  Tabuteau  flew  on  this 
machine  for  G  hours  l1/^  minutes  at  Bue,  covering  a  distance  of 
almost  300  miles.  This  record  was  later  bettered  by  Legagneux  on 
a  Bleriot,  and  again  broken  by  Tabutoau  himself,  who,  on  December 
30th,  won  the  1913  Michelin  prize  and  established  the  world's 


200  MONOPLANES    AND   BIPLANES 

record  for  distance  without  a  stop  by  flying  36^%  miles  in  about 
7%  hours.  No  railroad  train  in  the  world  goes  as  great  a  distance 
without  stopping. 

The  Frame. — The  frame  of  the  main  cell  is  made  oi'  the  cus- 
tomary wood  and  crosswire  construction.  The  planes,  however, 
project  out  in  front  of  the  front  line  of  struts,  and  are  not  flush 
with  them,  as  in  most  biplanes.  Outriggers  unite  the  long  curved 
skid  to  the  frame  in  front,  and  the  cell  at  the  rear  is  supported 
on  the  usual  H.  Farman-Yoisin  type  framework. 

The  Supporting  Planes. — The  main  surfaces  consist  of  a  frame 
of  wooden  ribs  and  cross  pieces,  covered  above  and  below  with 
canvas.  The  planes  are  curved  in  plan  at  the  ends,  giving  a  very 
graceful  appearance.  The  section  is  exceptionally  flat,  and  lacks 
altogether  the  pronounced  "dipping  edge."  The  camber  rise  is 
only  1/25  of  the  chord.  The  spread  is  36  feet,  the  depth  7.5  feet, 
and  the  area  510  square  feet. 

The  Elevation  Rudder. — At  the  front  is  situated  a  single-sur- 
face elevation  rudder.  The  twro  horizontal  planes  of  the  rear 
cell  have  pivoted  trailing  edges,  which  are  moved  jointly  with  the 
front  elevator.  The  control  is  by  a  rod  leading  to  the  front  ele- 
vator and  wires  leading  to  the  rear  flaps,  all  connected  to  the  bar 
upon  which  the  steering  wheel  is  mounted.  By  pulling  in  on  this 
bar  the  front  elevator  is  tilted  up  and  the  rear  flaps  tilted  up,  so 
that  the  machine  rises. 

The  Direction  Rudder. — Two  vertical  surfaces  are  hinged  to 
the  rear  struts  of  the  rear  cell.  These  move  jointly  and  serve  as 
the  direction  rudder.  They  are  moved  by  the  steering  wheel  and 
a  lever  and  wire  connection.  Turning  the  wheel  to  the  right, 
clockwise,  for  example,  will  cause  the  machine  to  turn  to  the  right. 

Transverse  Control. — The  rear  edges  of  both  planes  are  fitted 
with  hinged  ailerons;  these  are  controlled  by  foot  pedals,  a  dis- 
position which  has  recently  been  introduced  in  France  and  found 
very  instinctive.  These  pedals  are  hinged  at  the  base  and  are 
pushed  down  by  the  feet,  very  much  like  the  pedals  on  an  organ. 
Normally  the  pedals  are  at  a  60-deg.  position,  and  they  are  held 
there  by  a  wire  leading  over  a  pulley  to  a  counterweight.  Springs 


MONOPLANES    AND    BIPLANES 


201 


PLAN  AND  FRONT  ELEVATION  OF  THK  MAURICK  FARMAN  BIPLANE 


202 


MONOPLANES    AND    BIPLANES 


hold  all  the  wires  taut.  If  the  aeroplane  were  suddenly  to  tip  up 
on  the  right,  the  right  pedal  would  be  pressed  down.  By  this 
means  the  right  side  is  lowered  and  the  left  side  raised.  When 
making  turns,  if  it  is  found  desirable  to  use  the  transverse  control, 
then  the  pedal  on  the  side  to  which  it  is  desired  to  turn  is  pressed 
down.  The  controls,  wires,  etc.,  are  all  duplicate  in  this  machine, 
to  avoid  any  serious  consequences  in  case  of  breakage  of  any  part 
of  the  steering  gear. 

Tail. — The  horizontal  tail  planes  exert  a  considerable  lifting 
force.  There  are  no  vertical  keels.  In  former  machines,  vertical 
panels,  "curtains/'  were  used,  but  they  are  now  eliminated. 


SIDE  ELEVATION*  OF  THE  MAURICE  FARMAX  BIPLANE 

Propulsion. — In  general  this  type  is  equipped  with  a  Renault 
eight-cylinder  60  horse-power  air-cooled  motor.  A  Chauviere  "In- 
tegrate" propeller  is  mounted  on  the  cam  shaft.  It  is  9.8  feet  in 
diameter,  5.2  feet  pitch,  and  revolves  at  850  r.p.m.  The  motor 
is  placed  back  of  the  gasoline  tank,  which  is  at  the  rear  of  the 
seats. 

Seats. — At  the  center  on  the  lower  plane  is  placed  a  fusiform 
frame  inclosed  in  canvas.  At  the  front,  well  protected  from  the 
wind,  sits  the  aviator.  Maurice  Farman  was  the  first  biplane  con- 
structor to  adopt  full  protection  from  the  head  wind. 

A  passenger  seat  is  provided  at  the  rear  of  the  pilot,  and  is 
also  equipped  with  a  steering  gear. 

Mounting. — The  mounting  at  the  front  is  on  two  rubber-tired 


MONOPLANES    AND    BIPLANES  203 

wheels,  fitted  to  the  long  curved  skids  by  a  rubber  spring  fasten- 
ing. At  the  rear  are  two  smaller  wheels.  The  mounting  is  es- 
pecially strong,  since  the  skids  are  important  members  of  the 
framework,  and  transmit  the  shock  of  landing  over  the  entire 
structure. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  varies  from  1,100  to  1,250  pounds.  Tabuteau 
in  his  record  flight  made  a  speed  of  47  miles  an  hour  during  the 
first  two  hours,  and  then  the  speed  gradually  increased  until  at 
the  end,  he  was  flying  at  51  miles  an  hour.  Twenty-one  pounds 
are  carried  per  horse-power,  and  2.35  pounds  per  square  foot  of 
surface.  The  aspect  ratio  is  4.8  to  1. 

On  Tabuteau's  machine,  the  carrying  surface  was  increased  in 
size  by  the  addition  of  a  panel  on  each  side  of  the  upper  plane, 
resembling  greatly  the  construction  on  the  H.  Farman  "Type 
Michelin." 

References. — Quittner  and  Vorreiter,  Zeit.  ftir  Flugtech.  u. 
Motorluft.,  November  26th,  1910;  Aero,  October  19th,  1910, 
p.  313 ;  October  L'Grh,  1910 ;  November  2nd,  1910,  p.  350. 
November  23rd,  1910,  p.  414;  Flugsport,  October  19th,  1910; 
Allgemiene  Auto  Zeitung,  November  6th,  1910,  p.  1  ;  Aerophile, 
February  15th,  1909,  p.  81  ;  June  1st.  1910,  p.  251  :  Gabriel, 
M.  Zeit.  fur  Flug.  u  Motor,  November  26th,  1910,  p.  287; 
Revue  de  1' Aviation,  No.  41,  p.  89  ;  Revue  Aeronautique.  No. 
36,  p.  197;  Flight,  November  19th,  1910,  p.  948;  October 
22nd,  1910,  p.  862. 

10.      THE  GOUPY  BIPLANE 

One  of  the  first  machines  designed  by  M.  Goupy  was  a  triplane 
with  a  rear  stabilizing  cell,  built  for  him  by  the  Voisins  and  flown 
for  short  distances  in  the  spring  of  1908. 

The  Goupy  biplane,  built  in  the  Bleriot  factory,  resembles  the 
Bleriot  monoplanes  in  all  the  important  features  of  its  construc- 
tion with  the  exception  that  instead  of  one  large  plane,  two  smaller 
planes  are  used.  The  original  Goupy  (1909)  was  built  to  the 
plans  of  M.  Goupy  and  Lieut.  Calderara.  It  was  characterized  by 
a  front  horizontal  rudder,  which  has  since  been  abandoned,  and 
a  four-bladed  propeller. 

At  Rheims,  Ladougne  on  a  Goupy  won  many  prizes,  and  the 


204 


MONOPLANES    AND    BIPLANES 


Goupy  lias  often  exhibited  exceptional  stability  in  strong  winds. 
Frame. — The  central  frame  is  of  the  ordinary  Bleriot  wood 
and   cross-wire   construction.      The   main   biplane   cell   is   at   the 
front  and  at  the  rear  is  placed  a  smaller  cell. 


•       :.'•/ 


Courtesy  of  "Flight." 
M.  LADOUGNE  AT  DONCASTER,  OCT.,  1910 :  "VOLPLANING"  ON  His  GOUPY  BIPLANE 


MONOPLANES    AND    BIPLANES 


205 


Supporting  Planes. — The  most  distinguishing  feature  of  this 
biplane  is  the  staggering  of  the  main  planes,  i.  e.,  the  upper  one 
is  placed  ahead  of  the  lower  one.  It  is  claimed  that  this  disposi- 
tion gives  increased  stability  in  ^volplaning." 

Both  the  upper  and  lower  planes  have  ailerons  attached  at 
their  ends,  resembling  very  much  those  used  on  the  former 


PLAN  AND  ELEVATIONS  OP  THE  GOUPY  BIPLANE 

Bleriot  IX.  The  curvature  is  flat,  and  the  planes  have  a  con- 
siderable thickness.  The  spread  is  191/2  feet,  and  the  depth  G1/^ 
feet.  The  surface  area  is  237  square  feet. 

Elevation  Rudder. — At  the  rear  of  the  machine  is  a  horizontal 
biplane  tail.  The  lower  surface  of  this  tail  is  divided  into  three 
parts,  the  central  one  being  fixed  and  the  outer  ones  movable. 
These  outer  sections  move  jointly,  and  resemble  the  elevation  rud- 
der on  the  Bleriot  XI.  bis. 


206  MONOPLANES    AND    BIPLANES 

A  Bleriot  cloche  (explained  in  full  under  the  Bleriot  XI.)  is 
provided  for  control.  By  pulling  back  on  the  cloche,  the  incidence 
of  the  ailerons  is  increased,  and  at  the  same  time  the  rear  ele- 
vation rudder  is  turned  up,  so  that  there  is  a  very  strong  move- 
ment for  ascent,  the  front  rising  and  the  rear  descending. 

Direction  Rudder. — A  single-surface  direction  rudder  is  placed 
at  the  rear,  and  is  operated  by  movement  of  a  steering  wheel 
mounted  on  the  control  column.  No  foot  -lever  is  used.  To  turn 
to  any  side  the  wheel  is  turned  to  that  side. 

Transverse  Control. — The  ailerons  are  actuated  by  the  side 
to  side  movement  of  the  cloche.  If  the  machine  were  suddenly 
tipped  up  on  the  right  side  then  the  cloche  would  be  pulled  over 
to  the  right  thus  increasing  the  incidence  of  the  left  ailerons  and 
decreasing  the  incidence  of  the  right  ones.  This  pulls  the  machine 
up  on  the  left  side  and  down  on  the  right,  thus  correcting  the 
equilibrium. 

Keels. — The  fixed  portion  of  the  lower  plane  at  the  rear  and 
the  small  plane  above  it  act  as  keels  exerting  a  considerable  lift. 
There  is  also  a  small  tapering  vertical  keel  in  front  of  the  rear 
cell,  and  the  two  end  panels  of  the  small  rear  cell  are  "curtained" 
with  fabric,  thus  giving  two  more  vertical  keels. 

The  seat  for  the  aviator  is  placed  in  the  frame  at  the  rear  of 
the  main  cell.  A  passenger  seat  is  placed  well  in  front  of  this, 
over  the  center  of  gravity. 

Mounting. — The  mounting  is  essentially  on  three  wheels.  The 
two  at  the  front  are  mounted  on  the  customary  steel-tube,  rubber- 
rope  spring,  Bleriot  chassis.  There  is  a  single  wheel  at  the  rear. 
The  front  chassis  is  also  provided  with  two  small  but  very  strong 
skids. 

Propulsion. — A  50  horse-power  seven-cylinder  Gnome  rotary 
motor  mounted  at  the  front  drives  a  "Perfecta"  two-bladed  pro- 
peller 8*4  feet  in  diameter  and  4  feet  pitch  at  1,200  revolutions 
per  minute. 

Weight.  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  in  flight  is  nearly  1,OOD  pounds.  The  speed 
is  45  miles  per  hour.  Twenty  pounds  are  lifted  per  horse-power, 


MONOPLANES    AND    BIPLANES  207 

and   4.2   pounds   per  square   foot  of    surface.      The   aspect   ratio 
is  3  to  1. 

References.— Vligbt,  July  16th,  1910,  p.  553;  December  3rd, 
3010,  p.  993  ;  Fachzeit.  fur  Flugtechnik,  November  13th,  1910, 
p.  17;  L'Aerophile,  July  loth,  1910,  p.  317;  August  1st,  1910; 
V.  Quittner  and  A.  Vooreiter,  "Neve  Flugzeuge  in  Paris ;" 
Zeit.  fur  Flug.  und  Motor,  November  26th,  1910.  Aero,  Novem- 
ber 2nd,  1930,  p.  350;  L'Atrophile,  April  1st,  1909,  p.  150. 

11.      THE  NEALE  BIPLANE 

Although  similar  in  general  outline  and  type  of  construction 
to  the  Farman,  this  new  English  biplane  is  radically  different 
in  the  method  of  transverse  control,  in  the  absence  of  any  rear 
direction  rudder,  and  in  the  structure  of  the  surfaces.  Many  suc- 
cessful flights  have  been  made  by  the  Xeale  VII.,  and  the  odd  type 
of  transverse  control  used  appears  to  work  out  well. 

The  Frame. — The  framework  is  similar  to  the  general  wood 
and  cross-wire  main  cell  with  outriggers  now  so  commonly  em- 
ployed. 

The  Supporting  Planes. — The  planes  are  rectangular,  and  di- 
rectly superposed  and  have  an  incidence  of  9  degrees.  They  are 
made  of  one  layer  of  fabric,  sandwiched  in  between  the  flat  faces 
of  two  semicircular  ribs  screwed  together,  and  considerably  cam- 
bered. Horizontal  cross  braces  are  used  under  the  main  spars. 
This  construction  gives  great  strength  and  is  very  simple  and 
cheap.  The  planes  have  a  spread  of  34  feet,  a  depth  of  6l/2  feet, 
and  an  area  of  400  square  feet. 

The  Elevation  Rudder. — A  single  plane  elevator  in  front,  24 
square  feet  in  area,  and  the  trailing  edge  of  the  tail  surface,  are 
movable  jointly,  and  are  controlled  by  the  front  and  back  motion 
of  a  universally  pivoted  control  lever  (a  la  Farman).  To  rise, 
the  lever  is  pulled  in. 

The  Direction  Rudder. — The  main  object  in  the  design  of  this 
aeroplane  was  to  construct  a  machine  that  could  fly  across  the 
wind  easier  than  most  present  machines,  which  tend  to  head  up 
into  the  wind.  Hinged  to  the  front  strut  at  either  end  of  the 
main  cell  are  flaps,  or  balancing  planes  called  "screens."  They  are 
controlled  by  the  side-to-side  motion  of  the  lever.  These  serve  the 


208  MONOPLANES    AND    BIPLANES 

double  purposes  of  rudders  and  balancers.  Tbey  are  really  brakes, 
and  for  steering  act  as  such,  merely  retarding  one  side  of  the 
machine,  while  the  other  "skews"  about.  If  the  control  lever  is 
pulled  over  to  the  left,  the  left  screen  is  pulled  toward  the  center 
and  thus  "brakes"  that  side. 

Transverse  Control. — It  was  found  in  practice  with  this  ma* 
chine  that  a  5  deg.  deflection  of  a  screen  sufficed  for  a  sharp  turn. 
If  the  screen  on  one  end  was  sharply  set  at  45  deg.,  however,  the 
machine  was  found  to  tip  down  on  that  end.  This  is  due  to  the 
fact  that  a  large  mass  of  air  is  screened  off  suddenly  from  the 
planes,  and  this,  with  the  decreased  speed  of  this  end,  greatly  de- 


Courtesy  of  "Flight." 

SIDE  VIEW  OF  THE  NEALE  BIPLANE 

creases  the  lift  on  this  end.  The  entire  success  of  this  operation, 
however,  depends  on  its  suddenness.  The  screen  must  be  released 
immediately  after  deflection,  for  if  held  in  place  air  would  be 
drawn  in  on  the  other  side,  and  the  screening  action  destroyed. 
The  operation  is  repeated  in  quick  succession,  the  required  pull 
on  the  lever  being  quite  great. 

The  screen  rudders  are  121/4  square  feet  in  area.  A  sudden 
tip  down  to  the  left  would  be  corrected  by  quickly  moving  the  lever 
several  times  to  the  right. 

Tall. — There  is  a  single  horizontal  tail  surface  at  the  rear,  52% 
square  feet  in  area  and  having  a  spread  of  lO1/^  feet. 

Propulsion. — A  35  horse-power  four-cylinder  Green  engine 
drives  a  two-bladed  wooden  propeller,  7  feet  3  inches  in  diameter 


MONOPLANES    AND    BIPLANES 


209 


PLAN  AND  ELEVATIONS  OF  THE  NE-ALE  BIPLANE 


210  MONOPLANES    AND    BIPLANES 

and  4  feet  1%  inches  pitch,  at  950  revolutions  per  minute.  The 
motor  and  propeller  are  at  the  rear,  the  motor  being  mounted  on 
the  lower  frame. 

A  distinctly  H.  Farmaii  type  wheel  and  skid  chassis  is  used. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  about  1,0 JO  pounds;  2Sy2  pounds  are  lifted 
per  horse-power  and  2.5  per  square  foot  of  surface.  The  aspect 
ratio  is  5.2  to  1. 

References. — Fachzoit.     ftir    Flugtechnik,    No.    42.      p.      17  ; 
Flight,  October  8th,   1910,  p.   813. 

12.       THE   PAULHAN    BIPLANE 

The  new  Paulhan  biplane,  actively  discussed  in  aviation  circles, 
is  remarkable  only  for  the  strength  and  elasticity  of  its  structure, 
and  the  ease  with  which  it  can  be  packed  and  shipped. 

M.  Louis  Paulhan,  whose  great  exploits  as  an  aeroplane  pilot 
are  well  known,  has  here  made  a  happy  combination  of  a  new 
type  of  construction  and  the  customary  disposition  of  parts  in 
an  aeroplane,  that  is  distinctly  a  step  in  advance. 

Caille  flies  this  type  well. 

The  Frame. — The  frame  mainly  consists  of  two  lateral  girders 
about  61/2  feet  apart,  placed  one  over  the  other,  and  two  longitudi- 
nal girders,  attached  to  the  lower  one.  The  lateral  girders  form 
the  entering  edge  of  the  main  planes,  and  to  them  are  affixed  the 
numerous  ribs.  These  girders  are  connected  by  four  huge  wooden 
uprights  very  wide  and  thin,  fixed  by  a  .novel  leather  joint. 

The  longitudinal  girders  carry  the  elevator  at  the  front,  and1 
the  rudder  and  tail  at  the  rear.  There  is  a  total  absence  of  cross- 
wires,  the  necessary  bracing  being  obtained  by  the  use  of  a  few 
stout  steel  cables. 

The  girders  are  made  of  the  famous  Fabre  built-up  lattice- 
work, consisting  of  two  long  strips  of  wood  connected  by  a  line 
of  steel  triangular  plates,  the  whole  giving  extremely  low  weight 
and  resistance  as  well  as  great  strength. 

The  Supporting  Planes. — The  ribs  of  the  planes  are  very  flex- 
ibly fixed  to  the  main  cross  girders  by  an  ingenious  clip,  which 
is  very  easy  to  remove  or  replace.  In  the  canvas  of  the  planes. 


MONOPLANES    AND    BIPLANES  211 

are  sewn  pockets  corresponding  to  each  rib.  To  put  the  covering 
on,  these  pockets  are  merely  slipped  over  the  ribs  and  the  edges 
of  the  material  clipped  to  the  front  girder  and  to  the  rear  of 
each  rib.  This  is  an  exceptionally  practical  provision.  The  sur- 
faces of  the  planes  are  very  smooth  from  front  to  back  and  are 
unobstructed  by  any  cross  pieces. 

The  planes  have  a  spread  of  40  feet,  a  depth  of  5  feet,  and 
a  surface  area  of  320  square  feet. 


THE  PAULHAX  BH-LANE 
M.  Caille  is  seated  in  the  nacelle. 

The  Elevation  Rudder. — The  elevation  rudder,  at  the  front,  is 
small  in  size  and  very  strong.  It  is  operated  by  the  forward  or 
back  movement  of  the  controlling  column,  as  on  the  Curtiss  and 
M.  Farm  an. 

The  Direction  Rudder. — The  direction  rudder  is  suspended 
rigidly  by  cables  at  the  rear  just  in  front  of  the  horizontal  empen- 
nage. It  is  actuated  by  the  rotation  of  the  steering  wheel  on  the 
control  column,  clockwise  for  a  turn  to  the  right,  etc. 

Transverse  Control. — The  great  elasticity  of  the  planes  readily 
permits  of  their  being  warped  to  preserve  transverse  equilibrium. 
This  is  done  by  the  side-to-side  motion  of  the  controlling  column. 


212 


MONOPLANES    AND   BIPLANES 


39  o 


PLAN  AND  ELEVATIONS  OF  THE  PAULHAN  BIPLANE 


MONOPLANES   AND    BIPLANES  213 

A  movement  to  the  left,  pulling  down  the  rear  edge  of  the  plane 
at  the  right,  etc. 

Tail. — A  rear  horizontal  tail  or  empennage  is  provided.  It 
is  held  in  place  by  a  lever  which  can  be  moved  in  a  slotted  bar,  and 
which  is  locked  and  unlocked  by  a  key.  This  enables  the  inci- 
dence of  this  rear  plane  to  be  altered  at  will  and  made  weight  lift- 
ing or  not,  depending  on  the  load  to  be  carried. 

Propulsion. — A  50  horse-power  7-cylinder  Gnome  motor,  placed 
at  the  rear  of  the  nacelle,  drives  at  1,390  r.p.m.  a  "Xormale" 
wooden  two-blade  propeller,  8.9  feet  in  diameter  and  of  variable 
pitch. 

The  Nacelle. — The  seats,  the  steering  gear,  the  gasoline  tank, 
etc.,  are  all  inclosed  in  a  fusiform  body  of  aluminum  sheeting, 
called  the  nacelle.  This  is  suspended  rigidly  from  the  frame,  but 
in  no  way  rests  on  it.  It  is  very  light,  affords  great  comfort,  and 
is  an  especially  desirable  feature  because  of  the  ease  with  which 
the  motor  and  propeller  can  be  regulated  as  regards  their  adjust- 
ment and  mounting. 

The  Mounting. — Two  very  long  and  strong  skids  are  attached 
under  the  main  lower  lateral  girder  by  heavy  uprights,  and  ex- 
tend out  and  up  to  the  elevator.  At  a  point  about  below  the  center 
of  gravity  a  pair  of  heavy  rubber-tired  wheels  are  elastically 
mounted  to  the  skids.  At  the  rear  under  the  direction  rudder  is 
a  small  skid. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  950  to  1,050  pounds.  The  speed  is  48  to 
50  miles  an  hour.  The  aspect  ratio  is  8  to  1.  This  is  excep- 
tionally high.  Twenty-one  pounds  are  carried  per  horse-power, 
and  3.28  pounds  per  square  foot  of  surface. 

References. — Aero,  1910,  October  26th ;  November  2nd,  p. 
350;  November  9th;  November  16th;  November  30,  p.  430; 
"Neue  Flugzeuge  in  Paris,"  Zeit.  fur  Flugteeh  und  Motor 
November  26th,  1910;  Zrit.  fiir  T.uftschiffahrt,  No.  23,  p.  14, 
1910;  Allge.  Auto.  Zeit.,  3910,  No.  44,  p.  5:  No.  46,  p.  52; 
Flugsport,  November  2nd,  1910,  p.  675;  Flight,  October  22nd, 
1910,  p.  858  ;  Fachzeit.  fiir  Flug.,  November  13th,  1910,  p.  15  ; 
Aero.  (Am.),  December  10th,  1910,  p.  3:  Aircraft,  December 
10th,  1910,  p.  365  ;  L'Aero,  November  10th,  1910,  p.  2, 
No.  152. 


MONOPLANES    AND    BIPLANES 
13.      THE  SOMMER  BIPLANE 

IN  June,  1909,  Eoger  Sommer  purchased  a  biplane  constructed 
by  Henri  Farman,  and  on  July  3d  he  made  his  first  flight.  Scarcely 
a  month  later  lie  held  the  world's  record  for  duration  of  flight, 
having  flown  continuously  for  two  and  a  half  hours.  His  sudden 
jump  into  the  ranks  of  the  great  aviators  was  unusual  and 
showed  that,  after  .all,  it  was  not  so  hard  to  learn  to  fly  well.  At 
Rheims  and  at  Doncaster,  during  the  fall  of  1909,  he  won  many 
prizes,  but  shortly  after  this  gave  up  flying  on  the  Farman  aero- 
plane and  proceeded  to  design  and  construct  his  own.  On  January 
6th,  1910,  this  biplane  was  completed  and  tried  out  for  the  first 
time.  M.  Sommer  at  once  succeeded  in  making  three  perfect 
flights  of  several  kilometers  each,  and  after  three  days  of  experi- 
menting, a  long  cross-country  flight  was  made.  This  aeroplane  was 
also  operated  by  Lindpainter  and  Legagneux. 

On  December  31st,  1910,  the  Sommer  flew  109  miles  in  com- 
petition for  the  Michelin  trophy,  and  later,  an  especially  large 
Sommer  established  a  passenger  carrying  record. 

The  Frame. — The  materials  of  construction  of  the  frame  are 
chiefly  hickory  and  ash,  steel  joints  and  steel  tubing.  The  gen- 
eral character  and  appearance  of  the  frame  is  somewhat  similar 
to  that  on  the  Farman  machine. 

The  Supporting  Plane. — Two  identical  and  directly  superposed 
rigid  planes  carry  the  machine.  The  surfaces  are  made  of  rubber 
cloth  covering  wooden  ribs.  The  sectional  curvature  of  the  sur- 
faces is  not  as  highly  arched  as  on  most  other  types,  but  is  more 
nearly  as  in  the  Wright  machine,  a  very  even  and  gently  sloping 
curve.  The  spread  of  the  planes  is  33  feet,  the  depth  .5.2  feet,  and 
the  surface  area  326  square  feet. 

The  Direction  Rudder. — The  direction  rudder  consists  of  a  sin- 
gle surface  at  the  rear  of  10  square  feet  area.  It  is  operated  by  a 
foot  lever,  governed  by  the  aviator.  To  turn  to  the  right  this  lever 
is  turned  to  the  right,  etc. 

The  Elevation  Rudder. — At  a  distance  of  8.25  feet  in  front 
of  the  main  cell,  and  supported  on  framing  carried  down  to  the 
skids,  is  situated  the  single  surface  elevation  rudder.  This  is  gov- 


MONOPLANES    AND    BIPLANES  215 

-erned   by  a  large  lever  in  the  aviator's  right  hand,  which   when 
pushed  out  turns  down  the  rudder,  and  when  pulled  in  turns  up 
the  rudder,  thus  respectively  lowering  and  raising  the  aeroplane. 
Transverse    Control. — The    lateral    equilibrium    is    secured    by 


Photo  Edwin  Levick,  N.  Y. 


THE  SOMMER  BIPLANE,  RACING  TYPE 

The  lower  plane  is  cut  away  on  either  side,  thus  reducing  the  resistance  and 
enabling  the  aeroplane  to  attain  a  higher  speed.  Paillette  drove  this  ma- 
chine with  great  success  at  Rouen,  1910. 


216 


MONOPLANES    AND    BIPLAN KS 


means  of  two  ailerons,  one  placed  on  either  end,  at  the  rear  of 
the  upper  main  plane.  In  distinction  to  the  Farman  there  are  no 
ailerons  on  the  lower  plane.  The  control  is  by  side-to-side  motion 
of  the  large  lever  exactly  as  on  the  H.  Farman. 


SIDE  ELEVATION  AND  PLAN  OF  THE  SOMMER  BIPLANE 


MONOPLANES   AND   BIPLANES 


217 


Keels. — A  single  horizontal  plane  of  55  square  feet  area  and 
of  very  light  construction  is  placed  at  the  rear  and  steadies  the 
machine  longitudinally.  This  plane  is  movable,  although  it  does 
not  act  as  a  rudder.  A  lever  at  the  right  hand  of  the  aviator,  which 
automatically  "locks,"  enables  the  angle  of  incidence  of  this  surface 
to  be  varied  at  will,  thus  increasing  the  attainable  stability. 

Propulsion. — A  50  horse-power  Gnome  rotary  air-cooled  7-cyl- 
inder  motor,  placed  at  the  rear  of  the  main  cell,  drives  direct  a 
Chauviere  wooden  propeller  of  7  feet  diameter  and  5.2  feet  pitch 
at  1,200  r.p.m. 

The  Seat  for  the  aviator  is  fitted  more  comfortably  than  in 


V 


V 


V 


FRONT  ELKVATION  OF  THE  SOMMKR 


other  aeroplanes,  and  is  placed  on  the  front  of  the  lower  plane  at 
the  center. 

The  Mounting  consists  of  a  combination  of  two  large  wheels 
at  the  front  and  two  smaller  ones  at  the  rear.  The  front  wheels 
are  attached  by  rubber  springs  to  two  skids,  built  under  the  frame. 
The  skids  themselves  are  attached  to  the  main  cell  by  uprights,  the 
joints  being  made  of  a  springy  sheet  of  metal  bolted  to  the  fram- 
ing. This  adds  still  further  to  the  extremely  springy  character 
of  the  mounting. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  varies  from  800  to  900  pounds ;  the  speed  is  46 
miles  per  hour;  10  pounds  are  lifted  per  horse-power,  and  2.76 
pounds  carried  per  square  foot  of  surface.  The  aspect  ratio  is 
6.35  to  1. 


218  MONOPLANES    AND    BIPLANES 

Recent  Alterations. — For  racing  purposes  the  Sommer  has  re- 
cently been  altered.  The  two  end  panels  of  the  lower  surface  have 
been  eliminated,  very  much  as  on  some  of  the  Farman  machines. 
This  reduces  the  area  of  surface  to  25fi  square  feet,  and  makes  the 
loading  3.25  pounds  per  square  foot. 

References. — Aerophile,  v.   18,  p.   61,   February   1st,   1910, 
14.       THE   VOISIN    BIPLANE    (1909) 

The  Voisin  brothers  began  their  activity  as  constructors  of 
aeroplanes  as  early  as  1905,  when  they  constructed  gliders  for  both 
M.  Archdeacon  and  M.  Bleriot.  These  gliders  were  successfully 
operated  over  water,  being  towed  at  high  speed  and  lifted  from  the 
water  surface  by  motor  boats.  In  1900  the  Yoisins  built  a  motor 
machine  to  the  design  of  a  young  sculptor,  the  late  M.  Delagrange, 
and  subsequently  after  making  a  few  changes  in  the  design,  built 
a  machine  for  M.  Henri  Farman  which  was  the  first  truly  success- 
ful aeroplane  in  Europe.  The  design  of  this  type  remained  sub- 
stantially the  same,  except  for  the  addition  of  some  vertical  keels, 
This  type  was  formerly  very  extensively  used  abroad,  over  one  hun- 
dred having  been  manufactured.  It  is  not  so  widely  used  now. 

The  Frame. — The  frame  is  made  of  ash  with  steel  joints  and 
several  parts  of  steel  tubing.  It  consists  essentially  of  a  large 
box  cell  mounted  on  a  central  chassis,  and  a  smaller  box  cell  attached 
to  it  at  the  rear.  The  central  chassis  is  really  a  unit  in  itself; 
and  carries  the  wheel  mounting,  the  motor,  the  seat,  and  at  the 
front,  the  elevation  rudder. 

Tlie  Supporting  Planes. — The  main  supporting  planes  are  two 
in  number,  identical  and  directly  superposed.  They  are  made  of 
Continental  cloth  stretched  over  ash  ribs.  Their  shape  is  rect- 
angular. The  spread  is  37.8  feet,  the  depth  6.56  feet,  and  the  area 
496  square  feet. 

The  Direction  Rudder. — A  single  surface  of  25  square  feet  area 
placed  in  the  center  of  the  rear  cells  is  used  for  directing  the  ma- 
chine. It  is  operated  by  a  steering  wheel  and  cables  as  on  a  boat. 

The  Elevation  Rudder. — The  elevation  rudder  consists  of  a  sin- 
gle surface  of  41  square  feet  area  situated  at  the  front  end  of  the 


MONOPLANES    AND    BIPLANES 


219 


central  chassis.  It  is  governed  by  a  lever  system  attached  to  the 
axis  of  the  steering  wheel.  By  pushing  out  on  the  steering  wheel 
the  rudder's  inclination  with  the  line  of  flight  is  reduced  and  the 
machine  descends.  By  pulling  in,  the  machine  is  caused  to  ascend. 

Transverse  Control. — There  is  no  controlling  apparatus  for  the 
lateral  equilibrium  in  this  type. 

Keels. — The  two  horizontal  surfaces  of  the  rear  cell  about  130 
square  feet  area  act  as  keels  to  stabilize  the  machine  longitudinally. 
For  steadying  the  machine  transversely  and  for  keeping  it  to  its 


BUNAU-VARILLA  ox  A  Voisix  AT  RHEIMS   (1009) 

course,  there  are  provided  six  vertical  surfaces  (two  vertical  walls 
of  the  rear  cell  and  four  vertical  partitions  between  the  two  main 
supporting  planes). 

Propulsion. — A  50-55  horse-power  motor,   placed  on  the   rear 
of  the  central  chassis,  and  of  the  main  planes,,  drives  direct  a  two- 


220 


MONOPLANES    AND    BIPLANES 


blacled  metal  propeller,  7.6  feet  in  diameter  and  4.tf  feet  pitch,  at 
1,200  r.p.m.     Several  types  of  motors  have  been  used. 

The  Seat  is  placed  on  the  central  chassis  in  front  of  the  motor 
and  just  hack  of  the  front  edge  of  the  planes. 


/feel 


SIDE  ELEVATION  AND  PLAN  OF  THE  CELLULAR  VOISIN  (1909) 


MONOPLANES    AND    BIPLANES 


221 


The  Mounting  is  on  two  large  wheels  fitted  with  coiled  spring 
shock  ahsorbers  at  the  front  and  two  smaller  wheels  at  the  rear.  .To 
avoid  any  disastrous  results  if  the  machine  should  land  too  much 


FRONT  ELEVATION  OF  THE  CELLULAR  VOISIN 


A  CELLULAR  VOISIN  MAKING  A  TLRN 

"head  on"  a  small  wheel  is  fitted  to  the  front  end  OL  the  chassis 
directly  under  the  elevation  rudder. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  is  from  1,100  to  l.,25()  pounds;  the  speed  is 
35  miles  per  hour;  23  pounds  are  lifted  per  horse-power  and  2.37 


222  MONOPLANES   AND   BIPLANES 

pounds  per  square  foot  of  surface.     The  aspect  ratio  is  5.75  to  1. 

References. — Aeronautical  Jour.,  v.  12,  No.  46  ;  v.  13,  p.  60 ; 
Aerophile,  v.  15,  p.  232 ;  v.  16,  p.  38 ;  v.  17,  p.  488  ;  Aero- 
nautics (Brit.),  v.  1,  pp.  11,  18;  v.  2,  p.  20;  Sci.  AMERICAN, 
v.  97,  p.  292;  v.  98,  p.  92;  Locomocion  Aerea,  v.  1,  p.  78; 
Boll.  Soc.  Aer.  Ital.,  v.  6,  p.  288 ;  Flight,  v.  1,  pp.  19,  360, 
485,  505  ;  La.  Tech.  Moderne  No.  1,  p.  5  ;  Soc.  des  Ing.  Civ., 
v.  2  (1908),  p.  13;  Zeit.  Ver.  Deut.  Ing.,  v.  52,  p.  956;  Vor- 
reiter  A.  "Motor  Flugapparate" ;  Encyl.  d'Av.,  v.  1,  p.  19 ; 
Genie  Civil,  v.  55,  p.  341. 

15.      THE  VO1S1N  BIPLANE    (TRACTOR  SCREW   TYPE) 

This  machine,  built  by  the  Yoisins  and  first  experimented  with 
in  the  late  part  of  1909,  embodied  several  totally  new  departures 
in  the  construction  of  biplanes,  but  had  little  success.  The  Goupy 
and  the  Breguet,  aeroplanes  of  this  type,  however,  have  been  flown 
with  great  ease. 

The  Frame. — In  this  type  the  central  chassis  extended  far  out 
to  the  rear.  At  the  front  were  situated  the  motor  and  the  propel- 
ler, and  directly  behind  the  propeller  was  the  main  cell.  At  the 
extreme  rear  was  an  auxiliary  cell.  Ash.  steel  joints  and  steel 
tubing  were  used  throughout. 

The  Supporting  Planes. — The  two  carrying  planes,  placed  at 
the  front  on  the  central  chassis,  were  identical  and  superposed 
directly.  Their  spread  was  37  feet,  the  depth  5  feet,  and  the  area 
370  square  feet. 

The  Direction  Rudder  and  the  Elevation  Rudder. — The  rear 
box  cell  was  pivoted  on  a  universal  joint,  and  capable  of  being 
moved  up  and  down  or  to  either  side.  It  consisted  of  two 
horizontal  surfaces  about  80  square  feet  in  area  and  two  vertical 
surfaces  50  square  feet  in  area.  The  vertical  surfaces  acted  as  the 
direction  rudder,  when  the  cell  was  moved  from  side  to  side.  The 
horizontal  surfaces  served  to  control  the  elevation  when  the  cell  was 
moved  up  or  down.  The  movement  of  the  cell  was  controlled  by 
cables  leading  to  a  large  steering  wheel  in  front  of  the  aviator.  To 
turn  to  the  right,  the  cell  was  turned  toward  the  right.  To  ascend, 
the  inclination  of  the  cell  relative  to  the  line  of  flight  was  de- 
creased, the  leverage  desired  being  opposite  in  nature  to  that  of  a 
front  elevation  rudder. 


MONOPLANES    AND    BIPLANES 


223 


Transverse  Control. — There  was  no  transverse  control  in  this 
type. 

Keels. — Four  vertical  partitions  were  placed  between  the  two 
main  planes,  as  in  the  other  type  of  Voisin  biplane. 


Scale     of   /eel 


PLAN  AND  ELEVATIONS  OF  THE  EXPERIMENTAL  "TRACTOR  SCREW"  TYPE   VOISIN 
The  propeller  at  the  front  pulled  the  machine. 


224:  MONOPLANES    AND    BIPLANES 

Propulsion. — A  40  horse-power  4-cylinder  Yoisin  motor  placed 
at  the  front  end  of  the  chassis  drove  direct  a  two-bladed  metal 
propeller  of  7.2  feet  diameter  and  4  feet  pitch  at  1,300  r.p.in. 

The  Seat  was  situated  on  the  central  frame  at  the  rear  of  the 
main  cell. 

The  Mounting  was  on  two  large  rubber-tired  wheels  in  front, 
fitted  with  shock-absorbing  springs  and  a  single  wheel  at  the  rear. 


A  CLOSE  VIEW  OF  A  CELLULAR  VOISIN 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  was  from  800  to  9J>0  pounds;  the  speed  was 
said  to  be  50  miles  per  hour ;  19  pounds  were  lifted  per  horse-power, 
and  2.36  pounds  carried  per  square  foot  of  surface.  The  aspect 
ratio  was  7.4  to  1. 

References. — Aerophilo.  v.  17.  pp.  441,  485 ;  Aeronautics, 
v.  5,  p.  200 ;  Fachzeit.  fur  Flugtech.,  No.  30,  Oct.,  1909 ; 
Aero.,  v.  1,  p.  347;  Genie  Civil,  v.  55.  p.  341. 

16.       THE   VOISIX    BIPLANE    (TYPE    "BORDEAUX") 

Although  still  used  abroad,  the  old  Voisin  type  has  recently 
been  replaced  by  the  type  "Bordeaux,"  altogether  different  from 
the  old  type  in  control,  disposition  of  parts,  and  structure.  The 
front  elevator  and  the  vertical  "curtains"  are  entirely  eliminated. 


MONOPLANES   AND   BIPLANES 


225 


PLAN  AND  ELEVATIONS  OF  THE  "TYPE  BORDEAUX"  VOISIN 

The  front  elevator  is  eliminated  and  ailerons  on  the  upper  plane  take  the  place 
of  the  cellular  partitions. 


226  MONOPLANES    AND    BIPLANES 

The  type  "Bordeaux"  has  lately  had  many  conspicuous  suc- 
cesses abroad,  especially  in  the  hands  of  Metrot,  Bregi,  and  Bielo- 
vucie.  The  latter  made  his  brilliant  Paris-Bordeaux  flight  on  this 
type. 

The  type  "Bordeaux  Militaire,"  two-seated  and  equipped  with 
double  controlling  systems,  promises  to  be  one  of  the  most  prac- 
tical of  present  day  biplanes. 

The  Frame. — Steel  tubing  is  very  largely  used  in  the  frame- 
work, only  the  ribs  and  part  of  the  central  fuselage  being  made  of 
wood.  The  main  cell  carries  the  usual  chassis  of  steel  tubing  and 
fuselage  at  the  center.  The  outriggers  to  the  rear  are  also  very 
much  as  on  the  old  Voisin  type. 

The  Supporting  Planes. — The  planes  are  of  the  same  span,  but 
slightly  different  in  shape.  The  upper  one  alone  carries  ailerons. 
The  structure  of  the  surfaces  is  the  familiar  wooden  rib,  covered 
over  and  under  with  fabric,  the  longitudinal  spars  being  of  steel 
tubing.  The  spread  is  36  feet,  the  depth  Ql/2  feet,  and  the  surface 
area  395  square  feet. 

Elevation  Rudder. — At  the  rear,  back  of  the  horizontal  tail, 
and  forming  its  trailing  edge,  is  the  single-surface  elevator,  121/2 
feet  wide  and  2l/2  feet  deep.  This  is  operated  by  the  forward  and 
back  motion  of  the  controlling  column. 

Direction  Rudder. — Under  the  horizontal  tail  at  the  rear  is  the 
single-surface  direction  rudder,  which  is  turned  by  the  movement 
of  the  steering  wheel  fixed  on  the  controlling  columns. 

Transverse  Control. — At  the  rear  ends  of  the  upper  plane  are 
hinged  ailerons,  2~y2  feet  chord  and  9  2/3  feet  wide,  which  hang 
down  loose  when  the  machine  is  standing  still,  and  fly  out  in  the 
air  stream  when  in  flight.  They  are  controlled  by  foot  pedals  very 
much  as  on  the  M,  Farman,  excepting  that  the  counterweights  are 
not  used. 

The  two  controlling  systems  installed  for  the  type  "militaire" 
are  precisely  duplicates  of  each  other. 

The  Tail. — The  rear  horizontal  tail  surface  is  placed  at  a  con- 
siderable angle  of  incidence,  and  exerts  an  appreciable  lift.  It  is. 
41/2  feet  deep  and  I2y2  feet  wide. 


MONOPLANES   AND   BIPLANES 


227 


TWO   VIEWS   OF   THE  VOISIN    (TYPE    "BORDEAUX") 

The  engine  is  placed  very  nearly  at  the  center  and  two  sets  of  steering 
gear  are  provided 


228 


MONOPLANES    AND    BIPLANES 


Propulsion. — At  the  rear  of  the  central  fuselage  is  mounted  the 
motor,  which  must  be  of  55  horse-power  and  weigh  less  than  440 
pounds.  E.  N.  V.  60  horse-power  and  Gnome  motors  are  largely 
used.  A  Voisin  two-bladed  steel  and  aluminum  propeller,  driven 
at  1,100  r.p.m.  and  8.2  feet  in  diameter,  is  used. 

Mounting. — The  mounting  is  on  a  steel-tube  chassis  fitted  with 
two  large  wheels  and  coiled  spring  shock  absorbers,  under  the  front 


JBBB 


THE  VOISIN  (FRONT  CONTROL,  1911) 


MONOPLANES    AND    BIPLANES 


229 


of  the  cell,  a  small  wheel  on  the  nose  of  the  fuselage  as  a  special 
protection  when  landing,  and  two  skids  at  the  rear. 

Seats. — Two  seats  side  by  side  are  built  into  the  fuselage  just  in 
front  of  the  main  cell.  They  are  exceptionally  well  placed,  and  en- 
able the  pilot  to  have  a  clear  view. 

The  entire  machine  presents  a  very  simple  and  finished  appear- 
ance. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  speed  is  nearly  51  miles  per  hour.  The  aspect  ratio  is  5.6 
to  1.  The  weight  varies  from  1,309  to  1,550  pounds  with  full 


THE  VOISIN  (FRONT  CONTROL,  1911) 

load.     Twenty-eight  pounds  are  lifted  per  horse-power,  and  3.14 
pounds  per  square  foot  of  surface. 

An  added  departure  in  this  type  is  the  enlargement  of  the  carry- 
ing surface  by  the  addition  of  a  panel  on  either  end  of  the  upper 
plane,  as  on  the  M.  Farman  of  Tabuteau,  the  Type  Michelin,  etc. 

References. — Allge.  Auto.  Zeit,  No.  42,  p.  36  ;  No.  43,  p.  3, 
1910  ;  Aero,  1910,  November  2nd,  p.  350  ;  November  30th,  p. 
432;  Fachzeit.  fur  Flugtech.,  November  13th,  1910,  p.  17; 
Aerophile,  1910,  July  15th,  p.  318 ;  September  15th,  p.  411 ; 
Flugsport,  October  19th,  1910;  Zeit.  fur  Flugtech.  u  Motor., 
November  26th,  1910;  Flight,  1910,  June  25th,  p.  486; 
October  22nd,  p.  861. 

17.       VOISIN    BIPLANE     (FRONT    CONTROL,    1911) 

MM.  Voisin  Freres  have  constructed  a  type  of  biplane,  charac- 
terized by  the  absence  of  a  tail  and  the  grouping  of  the  elevation 


230  MONOPLANES    AND   BIPLANES 

and  direction  rudders  at  the  front,  carried  by  a  long  central  fuse- 
lage. This  fuselage  is  attached  at  the  rear  to  the  main  biplane 
cell. 

The  motor  is  a  50  horse-power  Rossel- Peugeot,  and  drives  direct 
a  two-bladed  metal  Voisin  propeller,  at  the  rear  of  the  supporting 
planes. 

The  lateral  stability  is  maintained  by  means  of  ailerons  opera- 
ted exactly  as  on  the  Voisin  (Type  Bordeaux). 

The  main  planes  have  a  span  of  39  feet,  a  chord  of  7  feet,  and 
an  area  of  380  square  feet. 

The  mounting  is  on  four  wheels,  two  at  the  front  and  two  at 
the  rear,  fitted  with  springs. 

The  aviator  sits  in  front  of  the  main  planes  in  the  fuselage. 
and  commands  a  clear  view  of  the  rudders  and  of  his  surround- 
ings. 

This  type  is  experimental,  but  it  has  displayed  good  stability 
and  speed,  and  rises  off  the  ground  very  quickly. 

18.      THE   WRIGHT  BIPLANE    (1909) 

As  early  as  1903  after  exhaustive  experiments  in  gliding  Wil- 
bur and  Orville  Wright  made  flights  in  a  motor-driven  aeroplane 
differing  little  from  their  present  well-known  type.  The  first  pub- 
lic flights  of  the  Wrights  were  made  in  September,  1908,  when  Or- 
ville Wright,  at  Fort  Meyer,  and  Wilbur  Wright,  at  Le  Mans, 
France,  astonished  the  world  with  their  consummate  skill.  On 
December  31st,  1908,  the  Michelin  prize  was  won  for  the  first 
time  by  Wilbur  Wright,  who  on  that  day  flew  for  2  hours  and  18 
minutes.  The  Wright  machine  to-day  holds  no  great  record  ex- 
cept altitude,  but  the  flights  of  Wilbur  Wright  at  New  York  in 
October,  1909,  and  those  of  Orville  Wright  at  Fort  Meyer  in  July, 
1909,  are  among  the  most  difficult  as  yet  negotiated.  Among  the 
biplanes  the  Wright  is  almost  twice  as  efficient  in  power  con- 
sumption as  any  other  type. 

Many  machines  of  the  Wright  type  are  being  flown  in  France, 
Germany,  Austria,  Italy,  and  England,  notably  by  Count  Lambert 
and  M.  Tissandier  in  France,  Capt.  Englehardt  in  Germany,  and 


MONOPLANES    AND    BIPLANES 


231 


Lieut.  Calderera  in  Italy.  In  this  country  the  Wright  machine 
has  been  widely  used,  by  Messrs.  Coft'yn,  La  Chapelle,  Hoxsey, 
Brookins.  and  Johnstone,  as  well  as  the  Wrights  themselves. 

The  altitude  record  is  held  by  the  Wright  machine,  the  late 
Arch.  Hoxsey  having  mounted  to  the  height  of  11,400  feet. 


ORVILLB  WRIGHT  AND  LIEUT.   LAHM   FLYING   IN  THE  GOVERNMENT 
ENDURANCE  TEST  AT  FORT  MYER,  VA.,  ON  JULY  27TH,  1909 

The  old  1909  Wright,  although  at  present  almost  entirely  dis- 
carded, was  a  type  that  should  not  be  forgotten. 

The  Frame. — Clear  spruce  and  ash  were  used  throughout  the 
frame,  which  is  very  solidly  but  very  simply  built.  The  cross  wires 
were  of  steel  and  made  to  fit  exactly.  All  exposed  parts  of  the 
frame  were  painted  with  an  aluminum  mixture. 


232 


MONOPLANES    AND    BJ  PLANES 


THE  1905)   WRIGHT   "MODEL  A."     PLAN  AND  ELEVATIONS 


MONOPLANES   AND  BIPLANES  233 

The  Supporting  Planes. — Two  identical  and  superposed  sur- 
faces made  of  canvas  stretched  over  and  under  wooden  ribs,  sup- 
ported the  machine  in  the  air.  Their  curvature  was  some- 
what flatter  than  the  usual  one  used,  and  the  surfaces  were 
3  inches  thick  near  the  center.  These  planes  were  6  feet  apart; 
they  had  a  spread  of  -il  feet,  a  depth  of  6.56  feet,  and  an  area  of 
538  square  feet. 

The  Elevation  Rudder. — In  the  1909  Wright  biplane  the  eleva- 
tion rudder  was  so  constructed  that  when  elevated  it  was  auto- 
matically warped  concavely  on  the  under  side,  and  when  depressed 
curved  in  the  opposite  way.  This  materially  added  to  the  rudder's 
force.  It  was  double  surfaced,  70  square  feet  in  area,  and  placed 
well  out  in  front,  being  supported  mainly  on  framework,  of  which 
the  mounting  skids  formed  a  part.  At  present  the  elevation  rud- 
der consists  of  a  single  surface  at  the  rear.  This  rudder  was  gov- 
erned by  a  lever  in  the  aviator's  left  hand.  To  rise,,  the  aviator 
pulled  the  lever  toward  him.  This  motion  was  formerly  transmit- 
ted to  the  rudder  mechanism  by  a  long  wooden  connecting  rod, 
causing  the  rudder  to  be  turned  upward  to  the  line  of  flight,  and 
consequently  causing  the  machine  to  rise.  To  descend,  the  aviator 
pushed  this  lever  away  from  him.  At  present  the  same  control  is 
used,  but  it  is  transmitted  by  wires  to  the  rear. 

The  Direction  Rudder. — The  direction  rudder  was  placed  in  the 
rear,  on  the  center  line,  and  consisted,  as  it  does  now,  of  two  identi- 
cal vertical  surfaces  of  23  square  feet  area.  This  rudder  was  gov- 
erned by  the  lever  in  the  aviator's  right  hand.  To  turn  to  the  left 
the  lever  was  pushed  out,  while  to  turn  to  the  right  it  was  pulled  in. 
But  this  motion  was  very  rarely  used,  since  the  side-to-side  motion 
of  this  lever  also  controlled  the  warping,  and  the  two  motions  in 
this  type  were  very  intimately  connected. 

Transverse  Control. — The  famous  warping  device  was  used  by 
the  Wrights  for  the  preservation  of  lateral  balance,  and  for  arti- 
ficial inclination  when  making  turns.  The  rear  vertical  panel  of 
the  main  cell  was  divided  into  three  sections.  The  central  one  was 
solidly  braced  and  extended  either  side  of  the  center  to  the  second 
strut  from  each  end.  From  these  struts  the  rear  horizontal  cross 


234 


MONOPLANES    AND    BIPLANES 


pieces  of  the  planes  were  merely  hinged  instead  of  being  continued 
portions  of  the  cross  piece  at  the  center,  and  the  two  end  vertical 
panels  on  either  end  were  not  cross  braced.  These  two  rear  end  sec- 
tions of  the  cell  were  therefore  movable.  The  entire  front  of  the 
machine,  as  well  as  the  actual  ribs  inside  the  surfaces,  however, 
was  perfectly  rigid,  there  being  no  helical  torsion  of  the  ribs  them- 
selves as  commonly  supposed.  Cables  connected  these  two  sections 
of  the  planes  together  and  led  to  the  lever  in  the  aviator's  right 
hand.  The  operation  was  as  follows:  If  the  machine  suddenly 


DE  LAMBERT  ox  A  WRIGHT  (1909) 


dipped  down  on  the  right  end,  for  example,  then  the  lever  was 
moved  to  the  left  side.  This  action  pulled  down  the  rear  right 
ends  of  the  surfaces,  and  at  the  same  time  pulled  up  the  rear  left 
ends  of  the  surfaces.  This  caused  ar.  increase  of  incident  angle  of 
the  outer  end  of  the  plane  on  the  side  depressed,  and  a  decrease  of 
incident  angle  0.1  the  opposite  side ;  th^  consequent  increase  of  lift 


MOXOPLANTES    AND    BIPLANES  235 

on  the  depressed  side  and  decrease  of  lift  on  the  raised  side  righted 
the  machine  at  once.  But  throughout  this  process  the  entire  front 
face  of  the  cell,  as  well  as  the  rear  central  section,  remained  per- 
fectly rigid  in  every  sense. 

For  turning  to  the  left  for  example,  it  is  evident  that  if  this 
same  lever  were  moved  in  a  circular  arc,  outward  and  to  the  left 
(very  much  as  a  trace  of  the  desired  turn)  then  not  only  would  the 
surfaces  be  warped,  so  as  to  raise  the  right  end,  but  also  the  direc- 
tion rudder  set  to  give  the  desired  change  of  direction,  and  the 
consequent  action  was  prompt  and  very  efficacious. 

In  actual  practice  the  direction  rudder  and  transverse  control 
of  the  Wright  machine  are  almost  never  worked  separately. 

Keels. — There  were  no  fixed  keels  on  the  Wright  1909  biplane. 
A  small  pivoted  vertical  surface  was  placed  in  front  to  indicate  any 
change  in  direction  of  the  relative  air  current. 

Propulsion. — A  25-28  horse-power  4-cylinder  Wright  motor 
drove  by  chains,  in  opposite  directions,  two  two-bladed  propellers. 
These  propellers  were  made  of  wood,  and  were  placed  at  the  rear 
of  the  main  cell,  one  on  either  side  of  the  center.  They  rotated 
at  400  r.p.m.,  and  were  8.5  feet  in  diameter  and  of  9-foot  pitch. 

Seats  were  provided  for  two,  the  outer  one  for  the  aviator.  They 
were  placed  on  the  front  edge  of  the  lower  plane  to  the  side  of  the 
motor. 

Formerly  the  Mounting  was  on  skids  only.  When  starting  the 
machine  was  placed  on  a  small  truck  and  run  over  a  rail  on  the 
ground.  At  present  wheels  are  used. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  was  from  1,050  to  1,150  pounds;  the  speed 
is  40  miles  per  hour;  41  pounds  were  lifted  per  horse-power  of  the 
motor,  and  2.05  pounds  per  square  foot  of  surface.  The  aspect 
ratio  was  6.25  to  1. 

Alterations. — The  dimensions  of  the  United  States  Signal 
Corps'  machine  and  that  built  by  the  Aerial  Company  of  France 
differed  in  that  the  spread  was  reduced  to  36  feet  and  the  surface 
area  to  490  square  feet. 

In  the  French  Wright  machines  of  Count  Lambert  and  M.  Tis- 


236  MONOPLANES    AND    BIPLANES 

sandier,  the  aviator  sits  next  to  the  motor.  When  instructing  these 
two  men  at  Pan  in  the  winter  of  1909,  Mr.  Wilbur  Wright  had 
fitted  to  the  machine  an  extra  lever  (to  control  the  elevation  rud- 
der) on  the  right  side  of  the  passenger  who  sat  next  to  the  motor. 


THE  WRIGHT  MACHINE  AT  WASHINGTON  (1909) 
The  old  derrick  and  starting  rail  are  shown  in  the  foreground. 

The  position  of  the  levers  for  the  passenger  was  therefore  the  re- 
verse of  the  usual  one,  the  lever  controlling  the  direction  rudder  and 
warping  being  at  the  left  hand.  Tissandier  and  De  Lambert  hav- 
ing learned  to  operate  the  machine  with  this  disposition  have  never 
changed  it.  But  they  in  turn  have  become  the  instructors  of  many 


MONOPLANES    AND   BIPLANES 


231 


purchasers  of  Wright  machines,  and  since  their  pupils  occupy  the 
outside  seat,  they  are  taught  to  control  in  the  normal  manner. 

References. — Aeronautics,  v.  3,  Nos.  3  and  4,  v.  5,  p.  170  ; 
Sci.  AMERICAN,  v.  99,  p.  140,  209  ;  Aeronautical  Jour.,  v.  12, 
p.  114  ;  Zeit.  fur  Luftschiff,  v.  13,  p.  6  ;  Aerophile,  v.  16,  p. 
470;  v.  17,  p.  488;  Boll.  Soc.  Aer.  Ital.,  v.  4,  p.  410;  v.  6, 
p.  ''88;  Locomocion  Aerea,  v.  1,  p.  78;  La  Tech.  Moderne, 
No.  1,  p.  5;  Encyl.  d'Av.,  v.  1,  p.  19;  Am.  Machinist,  v.  31 
(2),  p.  473;  Century,  v.  76,  p.  641  ;  Peyrey,  F.,  "Les  Hommes 
Oiseaux" ;  Bracke,  A.,  "Const,  de  1'Aerop.  Wright"  ;  Vor- 
reiter,  A.,  "Motor  Flugapparate"  ;  Genie  Civil,  v.  55,  p.  342 ; 
Zeit.  Ver.  Deut.  Ing.,  v.  53,  p.  1098. 

19.     THE  WRIGHT  BIPLANE  (MODEL  R) 

Probably  the  most  interesting  aeroplane  that  has  been  brought 
out  during  1910  is  the  small  Wright  "roadster,"  with  its  miniature 


THE  SPECIAL  WRIGHT  GORDON  BENNETT  RACER 
Orville  Wright  is  at  the  front  testing  the  engine.     The  propellers  are  in  motion. 

biplane  cell,  and  its  huge  propellers  spanning  almost  the  entire  ma- 
chine. This  latest  speed  and  reliability  product  of  the  Dayton 
inventors  has  excited  a  very  lively  interest,  and  without  doubt 
points  the  way  to  many  of  -the  improvements  that  the  future  holds. 
A  machine  of  this  type,  but  fitted  with  a  60  horse-power  8-cylinder 
motor  and  very  much  smaller  in  size,  was  to  be  driven  in  the  1910 
Gordon-Bennett  Eace  by  Brookins,  and  there  is  little  doubt,  with 
the  phenomenal  speed  it  had  already  displayed,  that  it  would  have 
won  this  race  from  Grahame- White  had  the  unfortunate  failure  of 
the  engine  not  occurred. 


238 


MONOPLANES    AND    BIPLANES 


The  regular  30  horse-power  type  of  this  machine  has,  however, 
proved  itself  a  very  good  one.  Both  in  speed  and  in  its  remarkable 
ability  to  gain  great  altitude,  this  machine  in  the  hands  of  Ogilvie, 
Brookins,  and  the  unfortunate  Johnstone,  has  exhibited  far 
better  qualities  than  many  foreign  machines  using  almost  twice 
the  horse-power.  The  speed  with  which  this  type  can  "climb"  is 
exceptional. 

The  Frame. — The  framework  follows  closely  the  regulation 
Wright  lines,  the  outriggers  and  rudders  being  similar  to  the  1910 


PLAN  AND  ELEVATIONS  OF  THE  WRIGHT  MODEL  R,  "ROADSTER  " 
Note  the  area  swept  through  by  the  propellers  in  comparison  to  the  span. 

Wright.     The  skid  and  wheel  mounting,  however,  is  quite  different 
in  appearance,  although  identical  in  principle. 

The  Supporting  Planes. — The  two  identical  planes  are  the 
smallest  yet  used  on  an  aeroplane.  The  shape  and  curvature  is  as 
on  the  other  Wright  machines,  excepting  that  they  project  quite  a 
distance  out  beyond  the  end  panels  of  the  cell.  The  planes  have  a 
spread  of  26%  feet  and  a  chord  of  3  feet  7  inches.  The  total  area 
is  180  square  feet.  On  the  Gordon-Bennett  racer  the  spread  was 
feet  and  the  surface  only  145  square  feet. 


ff 

MONOPLANES    AND    BIPLANES 


239 


The  Elevation  Rudder. — A  single  horizontal  surface  at  the  rear 
serves  as  the  elevator,  exactly  as  on  the  large  1911  Wright  biplanes. 
This  surface  is  8  feet  by  2  feet,  and  is  operated  by  the  new-type 
Wright  control  lever  placed  either  on  the  left  or  right  of  the  avi- 
ator. W.  Wright  and  Brookins,  for  example,  are  accustomed  to  op- 
posite positions.  The  control  lever  is  mounted  on  a  shaft,  and  to 


THE  60  HORSE-POWER  MOTOR  OF  THE  SMALL  WRIGHT   RACER,   AND  THE  CHAIN 
DRIVE  TO  THE  PROPELLERS 

it  is  fixed  a  drum  about  6  inches  in  diameter.  The  wires  for  the 
control  are  fastened  to  this  drum  by  short  chains,  and  are  thus 
moved  by  the  lever,  a  forward  movement  causing  descent,  etc. 

The  Direction  Rudder. — The  usual  biplane  direction  rudder  is 
used  and  is  operated  by  the  movement  of  the  lever  opposite  to  the 
elevation  rudder  lever.  By  moving  this  lever  and  its  drum  and 
chain  connection  forward  and  back  the  combination  warping  and 
rudder  movement  is  effected,  the  rudder  tending  always  to  steer  the 
machine  to  the  depressed  side.  The  drum  upon  which  the  direction 


240  MONOPLANES    AND    BIPLANES 

rudder  wires  are  attached  is  pressed  against  the  lever  by  a  spring 
and  is  thus  moved  with  it.  In  addition,  the  handle  at  the  top  of 
the  lever  is  made  movable  and  is  so  connected  to  the  drum  that 
by  moving  it  from  side  to  side,  the  direction  rudder  can  be  oper- 
ated alone  and  independently  of  the  warping. 

The  Transverse  Control. — The  transverse  control  is  by  means 
of  warping,  as  usual,  but  the  control  mechanism,  although  similar 
to  that  used  on  all  the  Wright  machines  at  present,  is  radically 
different  from  the  old  1909  type. 

On  the  same  shaft  upon  which  is  mounted  the  direction-rud- 
der lever  and  drum  is  another  drum  fitted  with  chains  leading  to 
the  wires  controlling  the  warping,  but  in  no  way  connected  with 
the  drum  to  which  the  direction  rudder  is  attached,  except  by  the 
spring  device  as  already  noted.  The  operation  of  the  warping  is 
done  by  the  forward  and  back  motion  of  this  lever,  and  no  more 
by  a  side-to-side  motion  as  formerly.  There  is  no  tail  other  than 
the  rudders,  which  in  their  normal  position  act  as  a  tail.  Two 
small  vertical  surfaces  on  the  skid  frame  at  the  front  are  used. 

Propulsion. — A  regulation  30  horse-power  Wright  motor  is 
installed,  and  drives,  as  usual,  by  chains,  two  wooden  propellers, 
8  feet  6  inches  in  diameter,  at  450  r.p.m.  In  the  "racer"  an  eight- 
cylinder  60  horse-power  motor  drove  the  propellers  at  525  r.p.m. 
The  detail  of  the  propelling  mechanism  is  exactly  as  on  other 
Wright  types. 

Mounting. — The  mounting  is  on  two  short  skids  built  down 
from  the  lower  plane.  On  each  skid  is  mounted  a  pair  of  wheels, 
the  axle  being  fastened  to  the  skid  by  a  rubber  spring  arrange- 
ment. 

On  the  "racer"  two  additional  wheels  were  placed  in  front, 
making  six  in  all.  The  chassis  on  the  "racer"  appears  to  have  been 
too  weak,  but  on  the  "roadster"  it  works  well. 

The  single  Seat  for  the  pilot  is  placed  as  usual  to  the  left  of 
the  motor. 

Weight,  Speed,  Loading  and  Aspect  Ratio. — 

The  total  weight  in  flight  is  about  760  pounds,  the  machine 
weighing  585  pounds  unmounted.  The  speed  of  the  Bracer"  has 


MONOPLANES    AND    BIPLANES 


241 


242 


MONOPLANES   AND   BIPLANES 


MONOPLANES    AXD    BIPLANES  243 

been  timed  by  the  author  at  67.5  miles  an  hour,  and  that  of  the 
"roadster"  at  54.5  miles  an  hour.  Wilbur  Wright  has  stated  that 
even  higher  speed  had  been  obtained.  The  pounds  carried  per 
horse-power  by  the  "roadster"  are  25.4,  and  14.3  by  the  "racer"; 
the  pounds  per  square  foot  are  4.20  for  the  "roadster"  and  5.92 
for  the  "racer/7  the  highest  loading  ever  carried  on  an  aeroplane 
up  to  the  present.  The  aspect  ratio  is  7.4  to  1. 

References. — Aeronautics,  December,  1910,   p.  192  ;  Aircraft, 
December,   1910,   p.  363. 

20.      THE  WRIGHT  BIPLANE    (1911)    MODEL  B 

The  new  Wright  passenger  biplanes  differ  from  the  1909  type 
in  that  the  front  elevation  rudder  is  eliminated  entirelv;  in  its 


MODEL  B  IN  FLIGHT 

This   photograph   shows   the   shape  of   the   planes   and    rudders   as  viewed   from 

underneath. 


place  a  small  single  surface  is  carried  at  the  rear,  and  either 
warped  up  or  down  or  turned  for  elevation  control,  depending  on 
the  manner  in  which  it  is  attached  to  the  frame.  The  entire  ma- 
chine is  resembled  closely  in  appearance  by  the  new  "roadster." 


244 


MONOPLANES    AND    BIPLANES 


PLAN  AXD  ELEVATION  OF  THE  WRIGHT  BIPLANE,  MODEL  B 


MONOPLANES    AND    BIPLANES  245 

The  type  of  construction  and  the  disposition  of  the  motor,  pro- 
pellers, etc.,  is  practically  the  same  as  on  the  older  types. 

The  chassis  is  now  fitted  with  wheels  attached  to  the  skids  by 
rubber  springs. 

The  control  is  by  means  of  the  new  "breaking"  lever  system 
(see  p.  288). 

The  new  aeroplanes  are  smaller  and  faster  than  the  old  ones. 
The  spread  is  reduced  to  39  feet,  the  depth  to  61/4  feet  and  the  area 
to  440  square  feet.  A  30  horse-power  motor  is  used  as  usual. 
Thirty-seven  pounds  are  lifted  per  horse-power  and  2.5  pounds  per 
square  foot  of  surface.  The  aspect  ratio  is  6.3  to  1. 

On  some  of  the  Wright  biplanes  in  Europe,  Gnome  motors  and 
single  propellers  have  been  installed. 


PART  III. 


COMPARISON  OF  THE 

TYPES-CONTROLLING  SYSTEMS- 

ACCIDENTS-THE  FUTURE 


CHAPTER    XII. 

COMPARISON  OF  THE  PROMINENT  TYPES 

In  comparing  the  successful  types  of  aeroplanes,  not  only  can 
several  interesting  contrasts  and  distinctions  be  drawn,  but  conclu- 
sions as  to  the  future  can  be  made.  For  this  purpose  the  aero- 
planes are  compared  according  to  the  following  essential  features: 

I.     Mounting 
II.     Eudders 
III.     Keels 

IV.     Position  of  seats,  motor,  etc. 
V.     Position  of  center  of  gravity 
VI.     Transverse  Control 
VII.     Aspect  Eatio 
VIII.     Incident  Angle 
IX.     Propellers 

X.     Structure  and  size 
XI.     Efficiency 
XII.     Speed  and  Flight 

I.     MOUNTING 

There  are  three  distinct  types  of  mounting: 

(a)  Skids  alone 

(b)  Wheels  alone 

(c)  Skids  and  wheels  combined 

The  necessity  of  providing  springs  on  a  heavy  machine  mount- 
ed on  wheels  has  frequently  been  emphasized.  M.  Bleriot  has  called 
attention  to  the  fact  that  a  high  speed  screw  generates  a  small 
gyroscopic  force  which  tends  to  resist  all  vibration  or  sudden 
changes  of  its  axis.  If,  therefore,  when  running  over  the  ground 
the  machine  be  suddenly  jarred,  the  propeller  is  likely  to  snap  off. 


248 


MONOPLANES    AND    BIPLANES 


This  has  often  been  experienced  by  M.  Bleriot  himself,  and  was 
only  obviated  by  the  use  of  a  very  springy  mounting. 

The  relative  merits  and  demerits  of  mounting  on  wheels  or 
skids  are  subjects  of  wide  discussion.  The  advantages  of  mounting 
such  as  in  the  old  Wright  machine  became  very  great  when  starting 
was  to  be  made  from  soft  soil  or  rough  land,  since  the  rail  upon 
which  the  machine  was  placed  could  be  laid  down  in  almost  any 


VIEW  FROM  AN  AEROPLANE  IN  FLIGHT 

Photograph  taken  from  the  Antoinette  in  mid-air  showing 
sheds  and  another  Antoinette  below.  The  top  of  one  wing 
appears  in  the  left  of  the  picture. 

kind  of  country,  whereas  wheels  require  a  certain  area  of  reason- 
ably smooth  and  hard  ground,  a  condition  not  always  met  with. 
A  machine  fitted  with  skids  can  withstand  rougher  landings,  and 
upon  alighting  stop  within  a  few  feet.  Furthermore,  by  using  a 
rail,  and,  in  addition,  as  was  often  done  with  Wright  machines,  a 
starting  impulse  given  by  a  falling  weight,  a  less  powerful  motor 
is  needed  for  starting. 


MOXOPLAXES    AXD    BIPLAXES 


249 


Nevertheless,  the  skid  mounting  has  a  great  disadvantage  in 
that  a  machine  fitted  with  them,  when  once  landed  away  from 
its  starting  rail,  cannot  again  take  to  flight.  This  has  caused  skids 
alone  to  be  disfavored  by  many  aviators.  Several  combinations  of 
skids  with  wheels  have  been  proposed  and  tried,  and  some  of  the 
recent  Wright  machines  have  had  wheels  fixed  to  the  skids  to  en- 
able a  fresh  start  immediately  after  landing.  These  combina- 


LOOKING  OVER  THE  Bows  OF  THE  ANTOINETTE  TO  THE  FIELDS 
AND  SHEDS  BELOW 

tions,  of  which  the  mounting  on  the  Farman  and  the  Sommer  are 
typical,  work  with  great  satisfaction  and  appear  at  present  to 
be  most  desirable  for  a  heavy  machine. 

The  conditions  of  landing  and  starting,  of  course,  govern  and 
are  governed  by  the  type  of  mounting  used.  In  landing  on  rough 
ground  with  a  Farman  type  chassis  the  wheels  are  likely  to  catch 
in  brushes,  etc.,  and  cause  considerable  damage.  Short  Bros.,  well- 
known  English  aeroplane  builders,  have  introduced  a  chassis  on 


250  MONOPLANES    AND    JUl'LANES 

which   the  wheels  used  for  starting  are  made  to   disappear   and 
landing  occurs  directly  on  the  skids. 

The  many  different  types  of  rubber  rope,  steel,  and  pneumatic 
springs,  are  all  about  equally  serviceable.  The  rubber  rope  spring 
introduced  by  Bleriot,  is  inexpensive,  quite  durable  and  very  light. 

Many  of  the  recent  Wright  biplanes  have  not  only  had  the  axle 
of  the  wheels  fitted  with  a  very  elastic  rubber  attachment,  but  have 
been  equipped  with  an  ingenious  device,  which  enables  the  aviator 
to  release  the  axle  and  cause  the  machine  to  rest  heavily  on  the 
skids,  while  at  the  same  time  small  hubs  dig  into  the  ground  and 
prevent  any  motion.  Hoxsey,  on  one  occasion,  at  Belmont  Park 
greatly  amused  the  huge  throng  watching  him  return  from  an 
attempt  at  an  altitude  record,  by  descending  to  the  ground,  near 
the  judge's  stand,  throttling  down  his  motor,,  anchoring  the  ma- 
chine by  the  device  described  above,  and  walking  off  to  deliver  his 
barograph  sheet,  while  his  propellers  were  turning  at  quite  an  ap- 
preciable speed.  He  then  returned  into  the  machine,  released  the 
"anchor,"  accelerated  the  motor,  and  took  to  flight. 

Whatever  the  character  of  the  mounting,  it  should  be  extremely 
strong.  There  is  little  doubt  that  had  the  Wright  Gordon-Ben- 
nett racer,  piloted  by  Brookins,  been  provided  with  a  stronger 
mounting,  the  wreck  that  occurred  would  not  have  been  so  dis- 
astrous. As  it  was,  this  machine,  carrying  an  enormously  heavy 
loading,  was  suddenly  deprived  of  the  major  part  of  its  motiA^e 
power,  and  lost  headway.  To  the  author,  who  was  closely  observing 
him  as  he  was  passing,  barely  a  hundred  feet  away,  Brookins 
appeared  to  be  gliding  to  the  ground,  with  skill  and  perfect  con- 
trol. As  soon  as  he  hit  the  ground,  however,  the  wheels  and  skids 
crumpled  like  paper,  and  the  machine  was  almost  totally  wrecked. 

On  aeroplanes  such  as  the  Curtiss  and  the  Grade,  where  the 
loading  is  light,  springy  mountings  have  been  found  unnecessary. 

It  is  likely,  however,  that  the  high  speed  aeroplane  of  the  fu- 
ture will  not  only  be  provided  with  a  very  solid,  elastic  mounting, 
but  will  be  projected  from  some  ingenious  starting  device  at  high 
velocity  so  that  it  may  be  quickly  launched  into  the  air. 


MONOPLANES    AND    BIPLANES 
II.       P.UDDERS 


251 


The  direction  rudder  in  most  of  the  main  types  is  placed  at 
the  rear.  The  1909  Cody  biplane  had  an  additional  direction 
rudder  in  front,  and  the  Voisin  (Front  Control  1911)  has  this  dis- 
position. All  the  monoplanes  excepting  the  new  Curtiss,  Valkyrie, 
Bleriot  '* Aero-bus"  and  Pntzner  have  their  elevation  rudders  at  the 
rear,  while  in  all  biplanes,  excepting  the  Breguet,  Dufaux,  Goupy, 


A  ROAD  AS  VIEWED  FROM  AN  ANTOINETTE  IN  FLIGHT 

and  the  1911  Wright 'and  Voisin  types  this  rudder  is  placed  out 
in  front.  Eudders  placed  at  the  rear  are  advantageous  in  that  they 
act  at  the  same  time  as  keels.  But  in  general  the  placing  of  the 
elevation  rudder  in  front  appears  to  offer  more  exact  control  of 
the  longitudinal  equilibrium. 

The  elevation  rudder  almost  always  exerts  some  supporting 
power.  Therefore,  when  placed  in  front  and  turned  up  for  ascent, 
the  support  is  increased  as  it  naturally  should  be.  But  when  this 


252  MONOPLANES   AND   BIPLANES 

rudder  is  placed  at  the  rear  the  movement  for  ascent  is  such  that 
the  supporting  power  of  the  rudder  is  decreased  and  usually  of 
negative  value^  so  that  instead  of  causing  the  front  of  the  machine 
to  rise,  it  merely  causes  the  rear  to  sink.  The  same  line  of  argu- 
ment shows  us  that  when  starting,  if  the  elevation  rudder  is  out  in 
front,  the  front  of  the  machine  lifts  off  the  ground  strongly  and 
is  followed  by  the  body,  while  if  this  rudder  be  in  the  rear,  when 
turned  to  give  ascent,  the  rear  merely  sinks  more,  and  not  only  is 
the  length  of  run  enormously  increased,  but  the  power  absorbed 
and  the  danger  incurred  are  greater.  This  is  obviously  a  bad  pro- 
vision. That  it  is  so  generally  used  on  monoplanes  seems  to  be 
caused  largely  by  the  placing  of  the  propeller  at  the  front. 

On  the  other  hand,  when,  as  on  the  (1909)  Wright,  the  ele- 
vator is  placed  forward,  it  is  exposed  to  the  elements,  and  its  great 
sensitiveness  is  bad  in  windy  weather.  When  the  elevator  is  placed 
behind,  as  on  the  monoplanes,  it  works  in  the  slip  stream  of  the 
propeller,  a  region  that  is  turbulent,  to  be  sure,  but  one  in  which 
the  air  motion  is  steady  and  constant  in  direction.  It  appears  in 
addition  that  moving  the  elevator  from  the  front  to  the  rear  of  a 
biplane  appreciably  increases  the  speed.  Farman  designed  a  bi- 
plane without  the  front  elevator  many  months  ago,  but  has  given 
it  up.  It  is  of  interest  to  note,  however,  that  the  most  recent  type 
of  Voisin  biplane  has  both  the  elevation  and  direction  rudders 
placed  up  front, 

In  some  of  the  Wright  biplanes  the  elevation  rudder  is  so  con- 
structed that  when  elevated  it  is  automatically  warped  concavely  on 
the  under  side,  and  when  depressed  curved  in  the  opposite  way. 
This  materially  adds  to  the  rudder's  force  due  to  the  peculiar  law 
of  aerodynamics  whereby  a  curved  surface,  under  the  same  condi- 
tions as  a  flat  surface,  has  a  greater  ratio  of  lift  to  drift.  The  re- 
duction in  size  of  the  rudder  that  is  thus  afforded,  and  its  flat 
shape,  when  normal,  greatly  reduce  the  head  resistance. 

In  so  far  as  the  action  of  a  biplane  is  usually  supposed  to  cause 
interference  of  the  two  surfaces,  and  greater  head  resistance,  it 
would  appear  as  if  the  biplane  rudders  as  used  on  the  1909  Wright 
and  the  1909  Curtiss  were  not  as  efficient  as  single  planes.  But  the 


MONOPLANES   AXD   BIPLAXES 


253 


structural  advantage  of  this  arrangement  is  great.  It  is  import- 
ant to  note  that  on  the  latest  Curtiss  and  Wright  machines  the  ele- 
vator is  a  single  plane. 

The  method  used  by  Grade  of  only  bending  flexible  surfaces,  in- 
stead of  turning  fixed  ones,  has  a  great  advantage  in  that  the  rud- 
ders after  being  used  spring  back  to  their  normal  position.  This 
method  has  been  adopted  on  several  other  types,  and  it  has  many 
considerations  of  safety  favoring  it. 


A  VIEW  IN  FRONTJ  FROM  AN  ANTOINETTE 

The  shadow  effect  is  due  to  the  propeller,  which  is  whirling 
at  high  speed.  The  dark  band  is  one  of  the  blades.  In 
the  middle  distance  is  a  biplane  in  flight,  and  in  the  far 
distance  a  patch  of  woods. 

In  almost  all  the  aeroplanes  that  are  flying  successfully,  except- 
ing, possibly,  the  Wright  and  the  Antoinette,  the  size  of  the  rudders 
is  generally  conceded  to  be  much  too  great.  This  is  clearly  upheld 
by  the  usual  remarkably  small  change  of  inclination  of  the  rudder 
that  is  necessary  for  a  change  of  direction.  This  ultra  sensitive- 
ness where,  as  in  some  machines,  a  movement  of  a  few  hundredths 


MONOPLANES    AND   BUM. .\\I-S 


of  an  inch  will  considerably  alter  the  state  of  equilibrium  of  the 
machine,  is  certainly  undesirable.  To  begin  with,  it  need  hardly 
be  pointed  out  that  over-sensitiveness  of  a  rudder  invites  danger- 
ous situations.  And,  furthermore,  if  a  rudder  is  extremely  sensi- 
tive, then  it  is  most  likely  too  big,  and  if  it  is  too  big,  then  it  is  ab- 


J 


THE  FARMAN  MONOPLANE  EXPERIMENTED  WITH  IN  THE  SPRING  OF  1910 

The  Gnome  motor  and  propeller  are  seen  revolving  rapidly  at  the  front.  The 
main  plane  'is  similar  in  construction  to  the  Farman  biplane  surfaces. 
Ailerons  are  used  for  transverse  control,  and  the  rudders  are  at  the  rear. 
This  machine  was  found  very  difficult  to  control.  Note  the  tense  position 
of  the  aviator  seated  back  of  the  main  plane. 


sorbing  power  that  could  be  put  to  better  use  elsewhere.  We  may 
therefore  look  to  a  great  decrease  in  the  size  of  rudders  as  a  devel- 
opment of  the  near  future. 

For  "volplaning,"  however,  as  pointed  out  in   Chapter  VII., 
Part  I.,  larger  rudders  would  give  added  safety. 


0 

MONOPLANES    AND    BIPLANES  255 

III.       KEELS 

Keels  on  aeroplanes,  like  keels  on  a  boat,  aid  in  the  sta- 
bility. But  on  an  aeroplane  they  are  "dead  surfaces/'  and  as  such 
have  the  disadvantage  of  offering  greater  expanse  of  surface  for 
wind  disturbance  to  act  upon.  Furthermore,  they  unquestionably 
deaden  the  motion  and  decrease  the  speed.  Tapering  keels  such  as 
used  on  the  Antoinette,  Pelterie,  Xieuport,  Etrich  and  the  latest 
Bleriot  XIV.,  offer  a  maximum  of  "entering  edge"  with  a  mini- 
mum of  area,  and  are  for  that  reason  more  advantageous  than  rect- 
.angular  shaped  ones. 

Separate  keels  are  entirely  absent  in  the  Wright  and  Santos 
Dumont.  The  tapering  bodies  on  the  Breguet  and  many  of  the 
monoplanes  are  a  distinct  advance. 

In  the  old  Voisin  type  use  was  made  of  several  vertical  keels, 
partitions,  placed  not  only  at  the  rear,  but  also  between  the  main 
surfaces  themselves. 

Keels  add  to  the  resistance  of  a  machine  the  skin  friction  and 
•consequent  power  absorption  of  such  surfaces  being  considerable, 
and  it  is  generally  conceded  now.  that  control  by  rudders  is  becom- 
ing so  perfected  that  any  inherent  stability  to  be  attained  by  use 
of  keels  at  the  expense  of  power  is  hardly  worth  the  while.  No 
special  form  or  combination  of  keels  that  have  so  far  been  designed 
.and  tried  have  really  succeeded  in  giving  any  kind  of  complete 
Inherent  stability. 

Keels  at  the  rear  of  a  machine  somewhat  on  the  order  of  a  bird's 
tail  are  nevertheless  found  advantageous,  and  we  can  expect  to  see 
such  surfaces  on  aeroplanes  for  many  years  to  come. 

Actual  practice  shows  that  they  do  increase  stability  and  tend 
to  hold  the  machine  to  its  course. 

The  reason  for  this  is  that  they  act  like  the  tail  of  an  arrow. 
If  the  rear  has  a  high  resistance  and  directive  surfaces,  and  the 
front  is  heavily  weighted,  like  the  head  of  an  arrow,  then  the  sta- 
bility is  much  more  perfect.  The  Antoinette  is  designed  in  this 
way,  and  in  its  dart-like  flight  certainly  gives  an  impression  of 
unusual  steadiness. 


256 


MONOPLANES    AND    BIPLANES 


Many  of  the  present  types  are  equipped  with  lifting  tails.  In 
the  Farman,  as  in  many  others,  the  propeller  blast  causes  the  tail 
to  lift.  This  is  considered  by  many  to  be  a  bad  provision,  because 
if  the  propeller  suddenly  stops,  the  tail  at  once  sinks,  and  this 
causes  the  dangerous  condition  of  loss  of  headway. 

IV.      POSITION    OF    SEATS,     MOTOR,    ETC. 

The  position  of  the  seat  and  the  motor  is  an  important  point 
in  aeroplane  construction.  On  monoplanes,  generally,  the  seat  is 


FRONT  VIEW  OF  THE  FARMAN  MONOPLANE 

placed  in  the  fuselage,  between  the  main  planes  and  well  to  the 
rear.  In  the  Antoinette  and  the  Breguet,  the  seat  is  placed  in  the 
frame  at  a  point  that  is  deemed  the  safest,  i.e.,  almost  everything 
else  will  break  before  the  aviator  is  touched.  On  the  Wright, 
Curtiss,  Farman,  etc.,  the  aviator  sits  at  the  front  of  the  main  cell. 
He  commands  here  an  uninterrupted  view  of  the  air  about  him, 
and  the  land  below  him. 

In  the  old  Antoinette  and  many  of  the  Bleriots  provision  for 
seeing  clearly  below  was  not  made.     This  was  very  detrimental, 


MONOPLANES    AND    BIPLANES 


257 


and  the  collision  that  occurred  at  Milan,,  when  Thomas  on  an 
Antoinette,  crashed  into  Dickson's  Farman  below  him,  merely  be- 
cause he  could  not  see  him,  made  this  defect  so  patently  evident, 
that  the  wings  of  the  new  Antoinette  at  once  were  notched  at  the 
rear,  so  that  the  aviator  could  obtain  a  view  of  the  region  below 
him. 

The  position  of  the  seat  on  the  Pischof,  Bleriot  XII.,  and  Dor- 
ner  is  advantageous  in  that  the  aviator  has  a  clear  view  below  and 
on  every  side,  can  also  watch  the  motor  in  front  of  him,  and  yet  is 
comfortably  placed,  inside  the  frame,  at  a  point  that  is  in  front 
of  the  propeller  and  fairly  safe. 


THE  CURTISS  MONOPLANE  BUILT  ESPECIALLY  FOR  THE  GOUDON  BENNETT   RACE 

It  was  not  very  successfully  flown.  The  single  plane  elevator  at  the  front  and 
the  side  ailerons  for  transverse  control  are  clearly  seen.  Note  the  simi- 
larity to  the  Curtiss  biplane  in  the  chassis  construction.  The  aviator  sits 
in  front  of  the  radiator. 

The  position  of  the  motor  at  the  back  of  the  aviator  as  on  the 
Curtiss  is  now  generally  considered  an  undesirable  one.  In  case 
of  a  sudden  plunge  to  the  ground,  and  a  consequent  breakage,  the 
motor  would  fall  out  of  the  frame  and  very  likely  pin  the  aviator 
under  it. 

Similarly  its  position  above  the  aviator  as  on  the  Grade,  Bleriot 
"Aero-bus,"  and  Santos-Dumont  is  dangerous,  in  that  it  would  very 
likely  crash  through  the  frame  and  fall  on  the  aviator's  head,  if  the 
machine  were  suddenly  to  lose  headway  and  sink  to  the  ground. 

In  many  cases  aviators  strap  themselves  into  their  seats,  and 


258  MONOPLANES    AND    BIPLANES 

the  recent  tragic  death  of  Moisant.  who  was  pitched  head-long  out 
of  his  seat  when  the  machine  suddenly  dove  down,  bears  out  the 
wisdom  of  this  measure. 

The  Maurice  Farman  and  the  Voisin  were  among  the  first 
prominent  biplanes  to  have  the  seats  and  fuselage  enclosed,  and  it 
is  now  recognized  as  quite  necessary,  especially  for  long  duration 
nights,  to  protect  the  aviators  from  the  head  wind.  The  enclosed 
fuselage  of  the  Paulhan  and  the  new  Farman  "type  Michelin," 
are  as  luxurious  and  as  comfortable  as  "torpedo"  body  automobiles. 

When  the  propeller  is  placed  at  the  front  there  is  still  more  rea- 
son for  protecting  the  aviator  as  the  air  stream  from  the  propeller 
is  very  disagreeable  and  likely  to  carry  with  it  fine  particles  of  oil, 
etc.  McArdle  in  his  flight  of  July  19th,  1910,  on  a  Bleriot,  be- 
cause of  the  film  of  oil  that  had  formed  over  his  eyes,  thought  he 
was  in  a  heavy  mist,  lost  his  way,  and  failed  to  find  the  Beaulieu 
grounds,  whither  he  was  bound. 

In  fact,  the  provision  of  a  proper  degree  of  comfort  for  the 
aviator  and  his  passengers  is  becoming  so  important  that  within  a 
few  years  we  may  actually  see  in  use  completely  inclosed  bodies, 
resembling  the  cabins  on  motor  boats.  Certainly  such  a  provision 
would  enable  aviators  to  guide  their  aeroplanes  to  much  higher 
altitudes.  A  light  canvas,  aluminum,  and  mica-glass  body  shaped 
in  stream  line  form  is  looked  forward  to  as  a  very  practical  inno- 
vation. 

V.       POSITION  OF  CENTER  OF  GRAVITY 

The  most  advantageous  position  of  the  center  of  gravity  is  be- 
ing actively  discussed  at  present,  and  it  appears  that  no  really  defi- 
nite conclusions  can  be  reached.  It  is  recognized  in  long  flights, 
that  the  gradual  diminution  of  the  gasolene  supply  affects  the  equi- 
librium of  the  machine,  unless  the  gasolene  tank  is  placed  over  the 
center  of  pressure.  On  some  of  the  "long-distance"  Bleriot  XL 
machines  it  is  deemed  necessary  to  put  the  gasolene  tank  low  in 
the  frame,  in  order  not  to  bring  the  center  of  gravity  too  high; 
this  position  of  the  tank  requires  a  pressure  feed  system.  The 
idea  in  the  new  disposition  of  surfaces  on  the  Farman  "Michelin" 


MONOPLANES    AND    BIPLANES  259 

seems  to  have  been  to  raise  the  center  of  pressure  so  as  to  be  able 
to  carry  an  increased  quantity  of  fuel  in  the  usual  position  on  the 
top  of  the  lower  plane,  without  any  pressure  feed  to  the  engine. 

The  frequent  pique  nez  of  the  Santos  Dumont  monoplanes, 
when,  on  landing,  they  stand  right  up  on  their  nose,  seems  alto- 
gether to  be  due  to  a  position  of  the  center  of  gravity  that  is  much 
too  high.  This,  of  course,  is  due  to  the  placing  of  the  motor  above 
the  plane. 

A  low  center  of  gravity,  as  on  the  Pischof,  is  said  by  some  to 


THE  "BADDECK  No.  2"  OF  MESSRS. 

MCCUBDY  AND    BALDWIN 

add  greatly  to  the  natural  stability  because  of  the  pendulum  effect, 
and  by  others  it  is  thought  to  be  detrimental  to  turning  manoeuvres 
and  transverse  stability.  Actual  observation  of  machines  with  a 
low  center  of  gravity  in  flight  shows  that  they  are  far  more  diffi- 
cult to  incline  transversely  than  a  machine  with  the  center  of 
gravity  about  in  line  with  the  propeller  axis.  Machines  with  the 
latter  provision  are  easier  to  handle  in  almost  every  way. 


260  MONOPLANES    AND    BIPLANES 

The  Antoinette  is  wonderfully  well  balanced,  and  the  con- 
centration of  the  weight  of  the  motor  at  the  front,  and  of  the 
operator  in  the  rear  of  the  main  surfaces  gives  perfect  results. 

It  is  doubtless  a  good  provision  to  have  the  propeller  axis  a 
little  above  the  center  of  resistance,  as  on  the  Wright,  because  the 
machine  then  tends  continuously  to  dive  downward,  and  therefore 
loss  of  headway  with  its  serious  consequences  is  not  so  likely  to 
happen. 

VI.       TRANSVERSE    CONTROL 

In  practice  the  lateral  stability  of  aeroplanes  is  inainty  pre- 
served in  five  ways : 

A.  Automatically. 

B.  By  warping  of  the  main  planes. 

C.  By  balancing  planes  ("wing  tips,"  or  "ailerons"). 

D.  By  sliding  panels  ("equalizers"). 

E.  By  vertical  surfaces  ("screens"). 

The  old  Voisin  is  the  only  type  for  which  automatic  lateral 
stability  is  claimed.  The  rear  box  cell  and  the  vertical  keels  be- 
tween the  surfaces  exert  such  a  forcible  "hold"  on  the  air  that  to 
displace  the  machine  is  difficult  and  in  all  ordinary  turmoils  of 
the  air  it  displays  exceptional  stability.  A  well-known  aviator  amus- 
ingly stated  at  Eheims  in  1909  that  were  a  Yoisin  tipped  com- 
pletely over  on  one  end  it  would  still  be  aero-dynamically  sup- 
ported, so  great  is  the  expanse  of  vertical  surface. 

Without  such  keels,  however,  the  lateral  balance  of  any  aero- 
plane is  so  precarious  that  some  form  of  control  is  necessary.  The 
machines  using  the  methods  of  warping  the  main  planes  for  the 
preservation  of  lateral  balance  include  in  addition  to  the  Wright, 
Breguet  and  Paulhan,  all  the  present  successful  monoplane  types 
except  the  Pfitzner,  Valkyrie,  and  Bleriot  "Aero-bus/' 

Because  of  the  structural  difficulty  of  rigidly  bracing  the  sur- 
face of  a  monoplane,  warping  is  an  ideal  form  of  control.  But 
the  rigid  structure  of  the  biplane  permits  auxiliary  planes  (wing 
tips)  to  be  more  easily  provided.  This  is  done  in  the  Farman, 
Cody,  Dufaux,  Neale,  Goupy,  Cnrtiss,  Sommer,  and  the  recent 
Voisin. 


MONOPLANES   AND   BIPLANES 


261 


Two  VIEWS  OF  CUETISS  ox  His  ALBANY  TO  NEW  YORK  FLIGHT 

These  two  methods  of  transverse  control  are  both  very  effica- 
cious, but  the  additional  resistance,  unaccompanied  by  any  increase 


262  MONOPLANES    AND    BIPLANES 

of  lift,  which  is  produced  by  balancing  planes,  perhaps  renders 
them  less  desirable  than  warping.  On  the  other  hand,  there  are 
objections  to  weakening  the  structure  of  the  main  surface  by  mak- 
ing it  movable.  Wing  flexing  weakens  the  spars  by  constant  bend- 
ing. 

Ailerons  on  the  trailing  edge  if  inclined  too  much  are  likely  to 
act  only  as  brakes,  while  ailerons  placed  between  the  planes  are 
found  to  be  very  inefficient. 

There  is  a  further  distinction  between  these  two  methods  of  con- 
trol which,  although  not  thoroughly  understood,  appears  to  bo 
borne  out  in  practice,  viz.,  when  a  plane  is  warped  the  action  tends 
not  only  to  tip  the  machine  up  on  one  side,  but  also  due  to  the 
helical  form  assumed,  there  is  a  tendency  to  turn,  which  can  oniy 
be  counteracted  by  a  vertical  rudder.  In  the  case  of  "wing  tips," 
however,  due  to  the  equal  but  contrary  position  in  which  they  are 
placed,  both  sides  of  the  machine  are  equally  retarded,  and  in  ad- 
dition,, since  the  main  surfaces  preserve*  the  same  shape  and  the 
same  angle  of  incidence,  this  tendency  to  turn  appears  to  be  absent. 
Mr.  Curtiss  states  that  for  correction  of  tipping  alone  he  makes 
no  use  whatever  of  the  vertical  rudder,  while  the  Wright's  claim 
that  it  is  always  necessary  for  them  to  turn  the  rudder  to  the  side 
of  least  incidence. 

Siding  panels  as  applied  to  the  Pfitzner  monoplane  and 
"screens"  as  used  on  the  Xeale  biplane,  represent  two  of  the  re- 
cently designed  methods  of  transverse  control  which  are  thought 
to  be  no  infringement  on  the  patent  rights  of  the  Wright  brothers. 
These  systems  have  not  been  adequately  tried  out  as  yet,  but  there 
is  no  reason  why  they  should  not  be  as  effective  as  the  system  of 
warping  or  the  use  of  ailerons. 

There  are  some  other  methods  designed  to  give  transverse  con- 
trol, and  it  seems  at  present  that  they  are  all  equally  reliable. 
Structural  individualities  of  the  types  of  aeroplanes  will  in  all  like- 
lihood persist  and  we  cannot  picture  the  machine  of  the  future 
with  any  one  kind  of  transverse  controlling  apparatus.  Wing  tips, 
ailerons,  are  widely  used  at  present,  bnt  further  progress  in  aerody- 
namics is  likely  to  show  no  that  warping  is  better. 


MONOPLANES    AND    BIPLANES 


263 


VII.       ASPECT   RATIO 

It  is  at  once  observable  from  the  values  given  in  the  tables  on 
page  265  that  the  ratio  of  spread  to  depth  (aspect  ratio) 
of  the  monoplanes  is  general!}7  less  than  that  of  the  biplanes. 
This  interesting  fact  is  due,  very  likely  to  the  structural  difficulty 
of  making  the  wing  of  a  monoplane  long  and  narrow,  and  at  the 
same  time  retaining  the  necessary  strength  without  undue  weight. 
The  Antoinette  builders  have  lately  decreased  the  depth  and 


• 


THE  OLD  "ANTOINETTE  IV,"  PILOTED  BY  LATHAM  OVER  THE  ENGLISH  CHANNEL 
ON  His  FIRST  UNSUCCESSFUL  ATTEMPT  TO  CROSS 

The  transverse  control  was  by  means  of  ailerons  on  this  machine. 


264  MONOPLANES    AND   BIPLANES 

increased  the  spread  of  this  type  of  monoplane,,  thus  increasing  its 
aspect  ratio,  but  the  framework  had  to  be  greatly  strengthened. 

The  Paulhan  biplane  has  the  highest  aspect  ratio  of  the  pres- 
ent types,  and  exhibits  remarkably  good  qualities. 

Theoretically  and  experimentally  the  value  of  this  quantity  is 
known  to  have  much  to  do  with  the  ratio  of  lift  to  drift;  but 
whether  or  not  in  actual  practice,  those  machines  like  the  Santos 
Dumont  and  Goupy  having  as  low  an  aspect  ratio  as  3  to  1  are 
really  inferior  in  their  qualities  of  dynamic  support  to  a  machine 
like  the  Paulhan  with  as  high  an  aspect  ratio  as  8  to  1,  is  difficult 
to  determine,  since  many  other  quantities  such  as  the  loading  and 
the  velocity  are  involved.  It  is  interesting  to  note  here  that  some 
of  the  large  soaring  birds,  notably  the  albatross,  may  be  considered 
aeroplanes  of  very  high  aspect  ratio. 

The  effect  of  aspect  ratio  upon  speed  is  not  discernible  on  com- 
paring the  types. 

Greater  stability,  however,  is  commonly  supposed  to  be  given 
by  a  high  aspect  ratio,  because  of  the  decreased  proportionate 
movement  of  the  center  of  pressure. 

The  advantage  and  effects  of  aspect  ratio  are  fully  discussed  in 
Chapter  VII,  Part  I.  It  may  be  indicated  here,  however,  that 
another  advantage  of  aspect  ratio  is  that  for  the  same  area  the 
decreased  movement  of  the  center  of  pressure  causes  a  smaller 
maximum  moment  tending  to  upset  the  aeroplane  (see  p.  82), 
and  therefore  permits  of  smaller  rudders  being  used.  It  is  valu- 
able also  to  note  that  experiments  in  aerodynamics  show  the 
drift  of  planes  with  different  aspects  to  be  about  the  same,  and  that 
the  lift  alone  increases  greatly  with  the  aspect  ratio. 

There  is  little  question  that  a  development  in  aeroplane  con- 
struction in  the  near  future  will  be  an  increase  of  the  aspect  ratio 
to  even  as  high,  possibly,  as  12  to  1. 

VIII.      INCIDENT  ANGLE 

The  incident  angle  (i.  e.,  the  angle,  the  main  inclined  surface 
makes  with  the  horizontal  line  of  flight)  varies  greatly  in  the  dif- 
ferent types.  The  Wright  biplane  is  noticeable  for  its  low  angle 
of  incidence  in  flight,  which  rarely  exceeds  two  degrees. 


MONOPLANES    AND    BIPLANES 


265 


Renard,  after  deductions  from  the  experiments  of  Borda,  as 
well  as  Langley  and  other  investigators,  have  enunciated  the  prin- 
ciple that  as  the  incident  angle  diminishes,  the  driving  power  ex- 
pended in  sustaining  a  given  plane  in  the  air  also  diminishes.  Wil- 


ASPECT  RATIO  TABLE  OF  MONOPLANES. 


R.  E.  P.  (1911)    6.5 

jBommer    /. 6.2 

Antoinette    6. 

R.  E.  P.  (1909)    5.75 

Pfitzner    5.17 

Valkyrie 5. 

Etrich    4.72 

Bleriot  XI.  2  Us 4.7 

Dorner    .  .4.6 


Bleriot  XI.  (Course)   4.5 

"          (Cross  channel)    4.35 

Meuport    4.23 

Hanriot   (1  seat)    4.2 

Tellier    4.2 

Bleriot  XII 4. 

Pischof    4. 

Grade  3.9 

Santos   Dumont  .   3. 


ASPECT  RATIO   TABLE   OF   BIPLANES. 


Paulhan    8.1 

Breguet  (40  to  50  H.  P.).  7.9 

Dunne .   7.6 

Voisin  (tractor)    7.4 

Wright  (Model  II)   7.4 

Breguet  (Course,  60  H.P.)   7.1 

Cody     (1911)   7.1 

Cody  (1909)    7. 

Farman  ("Michelin")  ...  6.8 
Curtiss  (Passenger)  ....  6.4 
Sommer  .  6.35 


Wright  (Model  B.)    .  .    . .  6.3 

"       (G.  B.  Racer)    .  .  6.3 

"        (1909)     6.25 

Voisin  (1909)    5.75 

Curtiss   5.65 

Dufaux    5.6 

Voisin   (Bordeaux)    5.6 

Xeale 5.2 

Farman   (1909)    5. 

M.  Farman   4.8 

Farman    (Course)    4.2 


Goupy    3. 

bur  Wright  states  that  "the  angle  of  incidence  is  fixed  by  the  area, 
weight,  and  speed  alone.  It  varies  directly  as  the  weight,  and  in- 
versely as  the  area  and  speed,  although  not  in  exact  ratio/'  Faraud 
concludes  that  small  angles  are  the  most  efficient  for  all  aeroplanes. 
There  is  for  each  aeroplane  a  most  efficient  angle  of  incidence  where 


2(>6 


MONOPLANES    AND   BIPLANES 


J 


MONOPLANES   AND    BIPLANES  267 

the  power  expended  for  flight  is  least.  In  flight  the  incidence 
should  be  kept  constant  at  this,  value  in  order  to  obtain  the  highest 
speed. 

The  Farman,  Voisin,  Bleriot,  Grade,  and  Sommer  have  an  angle 
of  incidence  when  first  starting  much  greater  than  when  in  flight. 
Since  this  involves  greater  drift  resistance  and  consequently  more 
power  necessary  to  attain  the  velocity  of  levitation,  and,  further- 
more, in  view  of  the  fact  that  aeroplanes  with  as  heavy  a  loading 
but  no  excessive  angle  are  able  to  rise  after  a  reasonably  short  run, 
it  would  appear  as  if  this  provision  were  unnecessary. 

There  exist  wide  variations  in  this  angle  as  observed  and  re- 
corded for  the  different  types,  many  of  the  present  machines  pre- 
serve their  equilibrium  daring  comparatively  large  changes  of  their 
longitudinal  inclination. 

In  general  the  incident  angle  of  the  monoplanes  is  greater  than 
that  of  the  biplanes.  The  most  common  angle  is  in  the  neighbor- 
hood of  5  to  ?  degrees.  But  in  the  Bleriot  "Aero-bus,"  an  inci- 
dent angle  of  12  or  13  degrees  is  often  used  in  flight. 

Incidence  will  very  likely  be  established  purely  by  the  lift-drift 
ratio  of  a  plane,  and  the  incidence  kept  as  constant  as  possible  to 
give  this  its  highest  value. 

IX.  PROPELLERS 

Most  of  the  aeroplanes  are  equipped  with  a  single  small  high- 
speed screw. 

The  Wright  and  the  Cody  are  the  only  machines  provided  with 
two  propellers  rotating  in  opposite  directions.  The  greater  ef- 
ficiency of  a  propeller  of  large  diameter  and  slow  revolution  over 
one  of  small  diameter  and  high  rotative  speed  has  attracted  much 
attention.  This  sc>ems  to  be  borne  out  especially  in  the  case  of  the 
Wright  machine,  in  which  more  thrust  is  obtained  per  unit  of 
power  than  in  any  other  type.  The  limit  of  rotative  speed  in  prac- 
tice is  in  the  neighborhood  of  1,500  r.p.m.,  and  in  most  types  the 
r.p.m.  exceeds  1,000.  Many  of  the  aeroplanes  use  Chauviere  wood- 
en screws,  for  which  an  efficiency  of  80  per  cent  is  claimed.  Metal 
propellers  are  not  used  much  now. 


268  MONOPLANES    AND    BIPLANES 

The  thrust  and  efficiency  of  the  various  propellers  are  about  the 
same  for  equal  sizes,  and  although  the  theory  involved  in  the  pro- 
peller is  very  little  understood,  the  experimental  methods  used 
have  enabled  the  design  of  propellers  of  as  good  or  better  efficiency 
than  those  used  in  marine  practice. 

The  position  of  the  propellers  at  the  front  in  most  of  the  mono- 
planes is  largely  a  matter  of  convenience  of  design.  The  swiftly 


DELAGRANGE  ON  His  MONOPLANE  (1909) 

This  was  one  of  the  first  Bleriot  machines  to  be  equipped  with  a  Gnome  rotary 
motor,  and  Dolagrange's  death  was  probably  due  to  the  fact  that  the  frame 
was  not  strong  enough  to  withstand  the  greater  forces  due  to  the  higher 
power  and  speed. 

moving  mass  of  air  from  the  propeller,  however,  exerts  an  added 
lift  when  thrown  back  on  the  plane.  At  the  same  time  this  action 
increases  the  resistance;  but  as  the  frame  resistance  of  the  mono- 
plane is  much  less  than  that  of  the  biplane,  the  propeller  can  be 
placed  in  front  without  very  serious  consequences.  The  Voisjn 
(tractor  type)  was  the  first  biplane  to  have  the  propeller  at  the 
front,  and  the  results  with  the  Breguet  and  Dufaux,  indicate  that 
this  is  in  no  way  detrimental  to  the  speed. 

It  is  generally  believed  by  aviators  that  much  better  results 


MONOPLANES   AND   BIPLANES  269 

could  be  obtained  by  the  use  of  propellers  of  15  or  20  feet  diameter 
rotating  slowly.  But  there  are  two  disadvantages  involved  in  this 
feature  of  construction  which  makes  its  adoption  in  the  machines 
of  the  future  rather  doubtful.  The  first  is  the  greatly  added  weight 
of  so  big  a  propeller  and  the  second  the  difficulty  of  building  a  good 
chassis  high  enough  to  permit  of  the  propeller's  rotating  freely. 

X.      STRUCTURE    AND    SIZE 

Most  engineers  are  impressed  with  the  fact  that  in  general  the 
structural  features  of  present-day  aeroplanes  are  "amateurish." 
This  is  no  doubt  well  founded  in  many  cases,  and  aeroplanes  have 
been  built  and  are  now  building  of  so  flimsy  a  character  that 
aviators  should  be  forbidden  by  law  to  fly  them.  But  when  the 
details  of  a  well-designed  and  constructed  type  like  the  Antoinette 
are  examined,  the  excellence  of  the  workmanship  is  at  once  ap- 
parent. 

The  general  type  of  aeroplane  structure  is  certainly  capable 
of  immense  improvement  and  modification.  The  primary  reason 
for  the  more  or  less  backwardness  in  this  respect,  is  that  the  great- 
er part  of  the  thought  and  time  of  constructors  has  been  spent 
on  motors.  Xow,  however,  motors  are  becoming  rapidly  a  second- 
ary consideration.  Any  number  of  good  ones  are  on  the  market, 
and  many  of  them  work  with  perfect  satisfaction  for  months. 

The  Fabre  type  of  construction  as  used  on  the  Paulhan  (ex- 
plained on  p.  2 ID)  is  a  distinct  step  in  advance,  as  is  also  the  metal 
construction  of  Breguet.  During  the  past  year  the  use  of  steel 
tubing  and  stronger  metal  parts  has  become  much  more  prevalent, 
and  the  era  of  the  all-steel  aeroplane  with  riveted  or  pin-connected 
joints,  I-bar  and  T-bar  struts  and  spars,  and  thin  steel  sheeting  for 
the  planes  is  not  far  distant.  In  monoplanes  for  example,  a  steel 
central  frame,  with  two  tension  members  bracing  the  planes  to  it 
below,  and  two  compression  members  above,  forming  a  rigid  truss, 
would  be  slightly  heavier  to  be  sure,  but  still  ever  so  much  stronger 
than  the  steel  ribbon  and  cross- wire  structure  now  used,  with  ten- 
sion members  above  the  plane,  in  many  cases  inactive  and  useless 
when  the  machine  is  in  flight. 


270 


MONOPLANES    AND   BIPLANES 


The  size  of  aeroplanes  varies  in  the  different  types,  but  between 
limits  that  appear  well  marked.  The  "waist-pocket"  aeroplane  is 
a  phantasy,  and  the  one  hundred  passenger  machine  is  still  in  the 
dim  future,  although  it  has  possiblities  of  success.  The  compara- 


PAULHAN  ON  His  Voisix.  OCT.,  1900 


tive  diagrams  of  the  aeroplanes  (see  Part  II)  give  an  insight  into 
their  relative  sizes,  in  far  better  fashion  than  words  can  do. 

XI.       EFFICIENCY. 

One  of  the  best  indications  of  the  general  efficiency  of  an  aero- 
plane is  the  amount  of  weight  carried  per  unit  of  motive  power. 
This  quantity  is  usually  termed  the  "pounds  per  horse-power,"  and 
is  arrived  at  by  dividing  the  total  weight  of  the  machine  in  flight 
by  the  horse-power  of  the  motor.  In  the  Tables  on  p.  274  and  p.  275 


MONOPLANES    AND    BIPLANES 

the  pounds  per  horse-power  for  each  type  are  given  numerically 
and  in  order  of  magnitude. 

The  Bleriot  XI.  (racing  model)  appears  at  present  to  be  the 
most  wasteful  of  power,  while  the  1909  Wright  was  by  far  the 
most  efficient.  It  must  be  borne  in  mind,  however,  that  the  Bleriot 
is  much  faster  than  the  Wright.  The  Grade,  Sommer?  Duf aux. 


T  ox  A  CROSS-COUXTRY  TRIP 

The  very  flat  nature  of  the  country  over  which  so  many  of  the  French  aviators 
make  extended  flights  is  evident. 

Wright  (racer)  and  Santos  Dumont,  appear  also  to  be  inefficient  in 
this  regard. 

The  Dorner,  Kieuport  and  Breguet  rank  high,  as  do  also  the 
Farman  passenger  machine,  the  Antoinette  and  the  Voisin  (Bor- 
deaux) . 


272  MONOPLANES    AND    BIPLANES 

There  is  no  special  variation  of  this  quantity  with  size,  how- 
ever, and  it  can  only  be  pointed  out  that  those  machines  using  a 
high  angle  of  incidence  appear  to  be  the  most  wasteful  of  power. 
The  Wright  has  the  lowest  incidence,  and  utilizes  its  power  best. 
But  the  use  of  two  propellers  instead  of  one  in  the  case  of  the 
Wright,  has  probably  much  to  do  with  its  power  economy.  Less 
pounds  are  lifted  per  horse-power  by  the  faster  machines,  but  their 
speed,  in  itself,  is  a  factor  of  efficiency. 

There  is  also  no  general  distinction  between  the  monoplanes 
and  the  biplanes  as  regards  the  weight  per  horse-power. 

A  more  direct  indication  of  the  aerodynamic  qualities  of  the 
aeroplanes  is  the  lifting  power  of  the  planes.  This  quantity,  termed 
the  "pounds  per  square  foot"  or  "loading."  is  arrived  at  by  dividing 
the  total  weight  by  the  area  of  the  sustaining  planes,  and  repre- 
sents the  number  of  pounds  carried  per  square  foot  of  the  surface. 

A  machine  carrying  a  very  light  loading,  however,  is  not  neces- 
sarily inefficient,  since  many  quantities  such  as  the  velocity,  the 
height  it  is  desired  to  attain,  and  other  questions  of  design,  enter 
into  the  determination  of  this  loading. 

As  regards  speed,  the  loading  can  theoreticaly  be  taken  as  a  di- 
rect indication  of  speed,  because  the  heavier  the  loading,  the  greater 
is  the  speed  necessary  for  support. 

There  are  many  surfaces,  however,  that  appear  to  be  more  effi- 
cient than  others,  in  that  they  can  carry  much  more  loading  with- 
out decreasing  to  any  great  extent  the  ease  with  which  the  aero- 
plane can  take  to  flight. 

The  effect  of  heavy  loading  on  the  landing  of  the  aeroplane  is 
naturally  to  make  the  landing  shock  very  great.  In  the  case  of  the 
Wright  (racer),  which  had  the  heaviest  loading,  it  was  necessary  in 
order  to  avoid  this  shock,  to  keep  the  propeller  running  at  full 
speed  even  when  alighting.  This  condition  is  undesirable  and  re- 
quires a  large  area  to  land  in. 

The  machine  with  heavy  loading  when  in  actual  flight,  however, 
is  less  likely  to  be  affected  by  slight  pulsations  of  the  air,  since  it 
tends  more  to  cut  through  them  because  of  its  small  buoyancy. 

A  heavilv  loaded  machine  cannot  soar  or  glide  as  well  as  a 


MONOPLANES    AND   BIPLANES 


273 


lightly  loaded  one,  nor  can  it  rise  to  as  great  a  height.  This  is  a 
distinct  disadvantage,  especially  in  view  of  the  recent  high  flying 
and  what  it  augurs  for  the  future  in  the  way  of  soaring  with  motor 
cut  off  for  long  stretches  of  time  and  at  great  elevations. 

Another  bad  effect  of  heavy  loading  on  an  aeroplane  is  the  diffi- 
culty it  has  of  starting  in  a  wind ;  and  the  ease  with  which  lightly 


IN  MID-CHANNEL 

loaded  aeroplanes  take  to  flight  in  squally  weather  was  especially 
noticed  at  the  recent  aviation  meetings. 

Heavy  loading,  however,  involves  also  the  question  of  economy, 
since  less  material  need  be  used,  and  the  design  can  be  made  more 
compact. 

In  the  Tables  on  page  27-1,  the  loading  for  each  type  is  given 
numerically. 


274 


MONOPLANES    AND    BIPLANES 


The  Grade  and  the  Wright  have  the  lightest  loading,  while  the 
Bleriot  XI.  (racer)  and  the  Wright  (racer)  have  the  heaviest.  It 
is  particularly  noticeable  that  in  general  the  monoplanes  are  more 
heavily  loaded  than  the  biplanes,  the  Grade  being  an  exception. 
This,  however,  is  not  accompanied  by  any  generally  remarkable 
high-speed  qualities  of  the  monoplanes,  as  would  be  expected,  but  is 
probably  due  to  the  interference  in  lifting  of  the  surfaces  of  a 
biplane  with  each  other. 

TABLE  OF  POUNDS  PER  SQUARE  FOOT  OF  SURFACE. 
MONOPLANES 


Bleriot  XI.    (Course)    .  .  .  5.76 

"       XII 5.3 

E.  E.  P.       (1911) 4.6 

Bleriot  XI.  (cross  channel)  4.5 

Xieuport    4.5 

E.  E.  P.  (1909)   4.4 

Hanriot   (1  seat)    4.15 

Bleriot  XI.,  2  bis   4.1 

Tellier    ,  .  4. 


Sommer 3.8 

Pischof 3.65 

Valkyrie    3.5 

Antoinette    3.33 

Etrich ..  3.2 

Pfitzner    3.2 

Santos   Dumont    3.1 

Dorner 3. 

Grade   .  .  2. 


TABLE  OF  POUNDS  PER  SQUARE  FOOT  OF  SURFACE. 
BIPLANES 


Wright  (G.  B.  Racer) ....  5.92 
Breguet    (Course  60  H.P.)    5.4 
Breguet  (40  to  50  H.P.) .  .   4.4 

Goupy    4.2 

Wright   (Eoadster)    4.2 

Curtiss    (Passenger)    ....   3.64 

Farman  (Michelin)    3.4 

Paulhan    3.28 

Dunne    3.2 

Voisin    (Bordeaux)    3.14 

Farman    (Course)    3. 

"        (1909)    2.8 


Cody   (1910) 2.8 

Sommer 2.76 

Cody      (1911)    .........   2.8 

Curtiss 2,5 

Keale    2.5 

Wright   (1911)    2.5 

Voisin    (1909)    2.37 

(tractor)     2,36 

M.  Farman   2,35 

Dufaux    .  . 2,1 

Wright  (1909)    2.05 


MONOPLANES    AND    BIPLANES 


275 


TABLE    OF    POUNDS    PER    HORSE-POWER    FOR    MONOPLANES 


Dorner    39. 

Nieuport    35. 

Antoinette   27. 

E.  E.  P.  (1909)   '27. 

Pfitzner    24. 

B.  E.  P.    (1911)    22.5 

Valkyrie 22.5 

Bleriot   (XL   2   bis)    21. 

"       (XII.) 21. 


Etrich   20. 

Tellier    19. 

Pischof    17.5 

Grade    17. 

Hanriot   (1  seat)    15.2 

Bleriot  (XL  Cross  Chan.).  14.4 

Sommer   14. 

Santos  Dumont 12. 

Bleriot.  XL   (Course)    7.5 


TABLE  OF  POUNDS  PER  HORSE-POWER  FOR  BIPLANES 


Wright  (1909)    41. 

"      (1911)     37. 

Farman    ("Michelin")     .  .   37. 
Breguet   (40  to  50  H.P.)..  36. 

Dunne    34. 

Neale    '. 28.5' 

Voisin    (Bordeaux)    28. 

Wright   (Boadster)    25.4 

Breguet   (Course  60  H.P.) .  25. 
Cody   (1909)     25. 

"     (1911)     25. 


Farman   (1909)    24. 

Yoisin   (1909)    23. 

Curtiss   (Passenger)    22.6 

Curtiss    22. 

Farman    (Course)     21. 

M.  Farman  21. 

Goupy   21. 

Paulhan 21. 

A'oisin  (tractor) 19. 

Sommer   16. 

Wright   (G.  B.  Eacer)    .  .  14.3 

Dufaux  11. 


XII.      SPEED  AND  FLIGHT 

The  speeds  of  these  aeroplane  types  are  given  numerically  in 
the  Tables  on  page.  277.  It  can  be  seen  at  once  that  the 
speeds  of  the  machines  are  all  very  much  alike,  the  monoplanes  not 
being  in  general  any  faster  than  the  biplanes.  The  Bleriot  XI. 
(racer)  and  the  Wright  (racer)  are  now  the  fastest,  and  the  Far- 
man (Michelin)  the  slowest.  It  is  noticeable  that  the  speeds  of 
aeroplanes  as  designed  at  present  seem  to  have  a  well-defined  limit 


276  MONOPLANES    AND    BIPLANES 

beyond  which  it  is  difficult  to  pass.  M.  Bleriot  in  1909  made  36 
miles  an  hour  on  a  monoplane  driven  by  a  25  horse-power  engine. 
Upon  subsequently  increasing  the  power  to  50  horse-power  he  was 
barely  able  to  reach  a  speed  of  54  miles  a  hour,  and  upon  increas- 
ing the  power  to  100  horse-power  this  year,  he  was,  with  the  same 
type,  able  to  make  only  58  miles  an  hour.  He  then  altered  the 
design  and  finally  Leblanc  and  Morane  were  able  to  make  over  68 
miles  an  hour. 

The  speed  shows  no  direct  variation  with  aspect  ratio  or  loading, 
and  higher  speed  appears  to  be  attained  mainly  by  an  excess  of 
power,  a  decrease  of  head  resistance,  and  a  small  size  of  plane. 

It  seems  doubtful  at  present  whether  we  can,  in  an  aeroplane, 
ever  get  up  to  a  speed  of  100  miles  an  hour.  It  is  quite  certain 
that  to  accomplish  this  the  general  type  of  aeroplane  we  now  have 
will  need  considerable  alteration. 

In  the  manner  of  flight  of  the  different  types  pronounced  dis- 
tinctions can  be  drawn. 

Probably  the  widest  variation  in  manner  of  flight  exists  be- 
tween the  Antoinette  and  Farman. 

The  flight  of  the  Farman  machine  can  best  be  described  as 
"sluggish."  The  enormous  resistance  of  this  machine  seems  almost 
visibly  to  hold  it  backhand  in  making  turns  the  action  is  slow  and 
"deadened/' 

In  contrast  to  this  is  the  strikingly  birdlike  flight  of  the  An- 
toinette. The  resistance  of  this  aeroplane  is  very  small,  and  conse- 
quently the  machine  darts  easily  through  the  air.  When  chang- 
ing the  direction  in  any  sense  or  when  correcting  its  stability,  the 
action  is  precise  and  well-nigh  instantaneous.  There  is  little  ques- 
tion that  the  Antoinette  answers  its  helm  better  than  any  other 
type. 

The  Bleriot  approaches  the  Antoinette  in  maniability,  and  the 
gracefulness  of  its  form  makes  it  also  appear  very  birdlike.  The 
Grade  because  of  its  light  loading  seems  especially  buoyant  on  the 
air,  and  the  other  types  have  characteristics  intermediate  between 
the  extreme  sluggishness  of  the  Farman  and  large  Wright  and  the 
preciseness  of  the  Antoinette. 


MONOPLANES    AND    BIPLANES 


277 


TABLE    OF    SPEED    OF     MONOPLANES 


Bleriot  XL  (Course)   ....    69.       Etrich 


R.  E.  P.    (1911)    60. 

Santos  Dumont 55. 

Sommer   54. 

Pischof    .  .53. 


51. 

Hanriot  51. 

Dorner   50. 

Bleriot  XI  (Cross  Chan.) . .  48. 

"       XII.  .  48. 


Tellier 53.       Valkyrie    46. 

Xieuport   52.5     Bleriot  XI.  2  bis 42. 

Antoinette   52.       Pfitzner    42. 

Grade   52.       R.  E.  P.  (1909)    39. 

TABLE    OF    SPEED    OF    BIPLANES 


Wright  (G.  B.  Racer)    . .  .  67.5 

Breguet  (Course  60  H.P.)  62. 

Wright   (Roadster)    54.5 

Breguet    (40  to  50   H.P.)  53. 

Voisin   (Bordeaux)    51. 

Dufaux    50. 

Paulhan   50. 

Voisin   (tractor)    53. 

Curtiss   49. 

M.  Farman   47. 

•Curtiss  (Passenger)    46. 


Voisin   (1909)    35. 

Sommer   46. 

Goupy    45. 

Farman   (Course)    44. 

Xeale 42. 

Wright       (1911)    42. 

Cody       (1911)    41. 

Wright   (1909)    40. 

Dunne 33. 

Cody  (1909)    37. 

Farman  (1909)    37. 

Farman  (Michelin)    34. 


278 


MONOPLANES    AND    BIPLANES 


I  <* 


ROUGIER  FLYINO  A  VOISIN  OVEK  THE  SEA  AT  MONACO 


CHAPTER  XIII. 

CONTROLLING  APPARATUS 

The  system  of  control  is  so  important  a  part  of  an  aeroplane 
that  it  is  well  worth  while  before  treating  of  accidents  to  consider 
the  principal  controlling  systems  that  are  in  use  more  fully  than 
is  done  in  Part  II.  in  order  to  bring  out  clearly  the  distinctions. 

It  must  be  borne  in  mind,  however,  that  the  system  of  control 
shown  for  any  one  type  is  not  necessarily  the  one  used  on  every 
machine  of  that  make.  Quite  the  contrary — there  are  wide  varia- 
tions from  the  standard  system  in  every  make,  dependent  pri- 
marily on  the  desire  of  the  purchaser.  For  example,  where  foot 
pedals  are  used  to  control  the  direction  rudder,  there  are  two  ways 
of  connecting  the  control  wires.  The  first  is  to  connect  them 
straight,  without  crossing  each  other;  the  control  requires  in  this 
case  that  to  turn,  4et  us  say,  to  the  left,  the  foot  bar  be  pushed  on  by 
the  left  foot.  Many  consider  this  an  uninstinctive  and  therefore 
undesirable  disposition  and  prefer  to  have  the  wires  crossed,  so 
that  to  turn  to  the  left,  the  right  foot  is  pushed  out  and  the  left 
foot  pulled  in,  the  motion  being  similar  to  that  of  an  axle  placed  at 
the  front  or  the  handle-bar  on  a  bicycle.  In  almost  all  the  foot  pedal 
controls  here  represented,  the  latter  disposition  is  given,  although 
in  some  types,  notably  the  Bleriot,  the  former  disposition  is  more 
widely  used.  In  many  cases  the  full  connections  of  the  control 
system  are  not  shown,  in  order  to  avoid  complications;  these 
sketches  are  merely  diagrammatic  and  distorted  for  explanatory 
purposes. 

1.      THE   ANTOINETTE 

In  the  diagram  on  p.  280  is  shown  the  controlling  system  of  the 
Antoinette.  The  aviator  seated  at  S,  has  a  wheel  at  his  right 
hand  RW,  controlling  the  elevation  rudder  E,  and  one  at  his 
left  hand  LW,  controlling  the  warping  of  the  main  planes.  A 
foot  pedal  P,  operates  the  direction  rudders  RR. 


280  MONOPLANES   AND   BIPLANES 

If  the  machine  were  suddenly  to  plunge  downward,  the  aviator 
would  quickly  turn  R\Y  in  a  counter-clockwise  direction  and  thus 
turn  up  E  and  right  the  machine.  The  transmission  by  crossed 
wires  from  the  drum  of  the  hand  wheel  to  the  arm  of  the  rudder 
can  readily  be  followed.  Due  to  the  variable  pull  of  his  propel- 
ler and  the  constant  shifting  of  the  center  of  pressure,  Latham  is 
almost  continuously  jockeying  the  elevation  rudder,  slightly,  up 
and  down,  as  one  who  has  seen  him  in  flight  could  clearly  observe. 

If  the  machine  tips  down  suddenly  on  the  left  side,  then  the 
wire  marked  "to  left  plane"  must  be  pulled  in,  in  order  that  the 


THE  CONTROLLING  SYSTEM  OF  THE  ANTOINETTE  MONOPLANE 

incidence  of  the  left  plane  may  be  increased.  To  do  this  the  cog 
mounted  on  the  strut  under  the  frame,  and  which  carries  witli  it 
the  cross  arm  holding  the  wires,  must  be  moved  in  a  counter  clock- 
wise direction.  Therefore  the  right  end  of  the  cross  arm  must  be 
pulled  up,  and  the  left  down.  By  following  the  wires  over  their  re- 
spective pulleys  it  will  be  at  once  observed  that  to  do  this,  the  wheel 
LW  must  be  turned  counter-clockwise.  Conversely,  to  tip  up  the 
machine  on  the  right  side,  LW  is  moved  clockwise,  thus  pulling 
in  the  wire  marked  "to  right  plane." 

To  turn  to  the  left,  the  aviator  pushes  on  the  pedal  P  with 
his  ri^ht  foot  and  thus  turns  rudders  RR  exactlv  as  on  a  boat.     If 


MOXOPLAXES    AND    BIPLANES 


281 


the  wires  were  not  crossed,  he  would  push  on  P  with  his  left  foot 
for  a  left  turn. 

The  control  system  of  the  Antoinette  is  ingenious,  but  hardly 
instinctive.  In  fact  this  is  one  of  the  hardest  machines  to  drive, 
with  the  possible  exception  of  the  Wright. 

2.    BLERIOT 

The  controlling  system  of  the  Bleriot  "militaire"  is  shown 
roughly  in  the  diagram  below.  The  mechanism  for  the  warping 
wires  consisting  of  a  shaft  and  drum  over  which  the  wires  lead 
down  to  pulleys  on  the  frame  strut  below  the  fuselage,  and  thence 
out  to  the  planes,  is  not  shown.  The  wires  from  the  foot  pedal  are 
here  shown  crossed,  although  the  more  usual  practice  appears  to 
be  to  have  them  leading  direct  from  the  ends  of  the  pedal  to  the 
rudder  bar. 


THE  CONTROLLING  SYSTEM  OF  THE  BLERIOT  MONOPLANE 

The  aviator  seated  at  S  operates  the  rudder  R  by  the  bar  P 
as  already  explained  for  the  Antoinette.  In  front  of  him,  be- 
tween his  legs,  is  the  cloche,  consisting  of  the  bell  C.  a  post  and 
the  small  wheel  W.  This  wheel  cannot  be  turned  and  is  merely 


282  MONOPLANES   AND   BIPLANES 

ornamental.     The  entire   cloche,  however,   is  universally  pivoted 
and  can  be  moved  forward  and  back  or  side  to  side. 

By  means  of  the  two  wires  marked  "to  left  plane"  and  "to 
right  plane/'  and  attached  on  the  side  of  the  cloche,  the  aviator 
controls  the  transverse  balance.  If  the  left  side  suddenly  tips  down, 
then  the  cloche  is  quickly  moved  over  to  the  right,  thus  pulling 
in  on  wire  "to  left  plane/'  and  increasing  the  incidence  of  the  left 
side.  This  action  actually,  however,  takes  place  through  the 
shaft  and  drum  (not  shown). 

.  The  flaps  of  the  elevation  rudder  EE,  are  controlled  by  the 
front  to  back  motion  of  the  cloche  acting  through  the  wires  on 
the  bell  and  the  double  lever  arm  below  in  such  a  way  that  to  cause 
ascent  the  cloche  is  pulled  back  towards  the  seat  S,  and  for  descent 
it  is  pushed  forward. 

The  Bleriot  control  is  instinctive  and  easy  to  acquire. 

3.  BREGUET 

On  p.  283  is  a  diagrammatic  sketch  of  the  Breguet  controlling 
system,  which  is  probably  the  most  instinctive  one  in  use.  All  the 
three  controls  are  united  at  one  place,  and  all  can  be  operated  sep- 
arately or  together  as  desired.  The  wire  connections  are  shown 
very  simply  here,  although  on  the  machine  itself  the  connections 
are  much  more  complicated.  The  manner  in  which  the  axle  of  the 
front  wheel  is  operated  in  combination  with  the  rudder  is  like- 
wise not  shown. 

The  wheel  W,  resembling  the  wheel  on  a  motor  boat,  is  mount- 
ed on  an  axle  at  the  top  of  a  strong  post.  This  post  is  mounted  on 
two  axes  at  right  angles,  thus  enabling  it  to  be  moved  side  to  side 
or  forward  and  back. 

The  side-to-side  motion  of  the  post  controls  the  warping  through 
wires  "to  left  plane"  and  "to  right  plane"  precisely  as  on  the 
Bleriot,  the  inclination  of  the  post  away  from  any  side  causing  that 
side  to  rise  up. 

The  rudders  R  and  E  are  rigidly  connected,  and  are  together 
mounted  on  a  single  universal  joint  at  the  rear  of  the  frame. 
Therefore  whenever  R  moves  from  side  to  side,  E  swings  around 
from  side  to  side  with  it  and  vice  versa. 


MONOPLANES    AND   BIPLANES  233 

To  ascend  the  aviator  pulls  the  post,  wheel  W  and  all  towards 
Mm.  This  turns  up  the  tail  E  and  ascent  follows. 

To  turn  to  any  side  the  wheel  W  is  turned  exactly  as  on  an 
automobile  or  motor  boat.  A  combined  action  of  warping  and 
rudder  for  turning  is  also  rendered  possible  by  this  system. 

It  is  of  importance  to  point  out  that  in  this  type  of  control,  th'e 
aviator  has  nothing  to  hold  on  to  but  wheel  W.  and  can  therefore,  if 
expert,  control  the  entire  machine  with  one  hand. 

No  simpler  controlling  apparatus  has  ever  been  used,  and  there 


THE  BREGUET  CONTROLLING  SYSTEM 

is  no  doubt  that  this  type  has  therein  an  immense  advantage  over 
all  others. 

4.  CURTISS 

The  outstanding  feature  of  the  Curtiss  system  shown  in  the 
diagram  on  page  284  is  the  operation  of  the  side-control  by  a  brace 
BB,  fitting  around  the  back  and  arms  of  the  aviator  and  pivoted 
on  the  seat  S. 

A  A  are  the  ailerons  of  the  right  side  mounted  on  the  trailing 
edges  of  the  planes  with  a  small  steel  rod  between  them,  as  used 
on  many  of  the  recent  Curtiss  biplanes.  Wires  lead  from  them  to 


284  MONOPLANES    AND    BIPLANES 

the  back  of  the  brace  as  shown.  If  the  machine  suddenly  tips 
down  on  the  right  side,  it  will  be  necessary  to  turn  down  AA,  and 
thus  lift  up  the  side.  This  is  done  by  a  very  natural  movement 
— i.  e.,  the  aviator  leans  towards  the  left  away  from  the  lowered 
side. 

In  front  of  the  seat  S  is  pivoted  a  post  capable  of  front  to  back 
motion,  and  upon  which  is  mounted  a  wheel  W. 

The  direction  rudders  RR  are  controlled  by  wheel  W  exactly  as 
the  rudder  on  a  boat.  To  turn  to  the  right  wheel  W  is  turned 
clockwise. 


THE  CUKTISS  CONTROLLING  SYSTEM 

The  control  post  is  connected  by  a  long  strut  L  to  the  elevation 
rudder  E  as  shown.  On  the  recent  Curtiss  machines  the  elevation 
rudder  is  a  single  plane.  By  pulling  the  wheel  and  post  towards 
him,  the  aviator  will  obviously  turn  up  the  elevator  E  and  will 
therefore  ascend.  To  descend  the  wheel  and  post  are  pushed  for- 
ward thus  turning  down  E. 

5."  ETRICH 

The  system  of  control  of  the  Etrich  monoplane  shown  in  thf 
diagram  on  p.  285  appears  at  first  hand  to  be  quite  complicated,  but 
it  is  really  very  instinctive  and  works  well  in  practice. 

A  steering  wheel  W,  governing  the  warping  of  the  planes,  is 
mounted  on  a  post  which  can  be  moved  forward  and  back  to  con- 


MONOPLANES    AND    BIPLANES 


285 


trol  the  elevation  rudder  E.  Two  foot  pedals  PP  control  in  uni- 
son the  direction  rudders  RE,  and  the  wheels  on  the  mounting 
chassis  M. 

If  the  machine  suddenly  tips  down  on  the  left  then  the  wheel 
W  is  turned  clockwise,  thus  increasing  the  incidence  of  the  left  side 
and  turning  up  the  rear  of  the  wing  on  the  right  side.  The  turbine 
effect  that  is  said  to  take  place  on  this  lowered  side  has  already 
been  explained  on  p.  123. 


THE  SYSTEM  OF  CONTROL  OF  RUDDERS.  ETC.,  ON  THE  ETRICH  MONOPLANE 

The  forward  and  back  motion  of  the  post  for  control  of  the 
elevator  E  is  exactly  as  on  the  Breguet. 

To  turn  to  any  side  the  foot  pedal  on  that  side  is  pressed 
down.  This  not  only  turns  the  rudders  but  also  the  wheels  on  the 
chassis  as  on  an  automobile.  The  wire  connections  must  be  fol- 
lowed through  in  order  to  understand  this  movement.  To  turn  to 
the  left  for  example,  the  left  pedal  P  is  pressed  down. 

6.    FAR  MAN 

The  Farman  single  lever  and  foot  pedal  control  shown  in  the 
diagram  on  p.  286,  is  probably  the  most  widely  used  at  present. 
A  large  lever  L  mounted  on  a  universal  joint  is  moved  forward 


280 


MOXOPLAXES    AXD    BIPLANES 


and  back  for  control  of  the  elevators  EE',  and  side  to  side  for  con- 
trol of  the  ailerons.  A  foot  bar  P  controls  the  direction  rudders 
ER  in  the  usual  manner. 

The  two  parts  of  the  elevation  control  consisting  of  the  single 
plane  E  at  the  front  and  the  rear  flap  E'  of  the  upper  deck  of  the 
rear  cell,  are  moved  jointly  by  the  lever  L.  Pushing  lever  L  for- 
ward will  cause  E  to  be  turned  down  and  also  E'  to  be  turned 
down,  so  that  the  machine  will  descend.  To  ascend  the  lever  is 
pulled  in. 


THE  FAUMAN  CONTROLLING  SYSTEM 

If  the  left  side  suddenly  tipped  down  then  the  lever  would  be 
moved  over  to  the  right  as  shown.  This  movement  acts  by  wires 
on  the  left  ailerons,  and  pulls  them  down,  thus  increasing  the  lift 
on  that  side  and  causing  the  machine  to  rise  on  that  end.  At  the 
same  time,  however,  the  wires  leading  to  the  ailerons  on  the  right 
side  are  slacked  and  they  merely  flap  freely  in  the  wind  stream. 

This  control  is  very  simple  and  is  about  as  easy  to  acquire  as 
the  Bleriot. 

For  safety  the  wires  leading  from  the  lever  to  the  ailerons 
and  rudders  are  made  double. 


f  "  -  .' 

MONOPLANES    AND    BIPLANES  287 

7.    HANRIOT 

The  Hanriot  control  shown  on  this  page  resembles  the 
Antoinette  excepting  that  levers  are  used  instead  of  wheels.  A 
foot  pedal  P  operating  the  rudder  K  is  used  in  the  usual  fashion. 

EL.  a  lever  in  the  aviator's  right  hand,  can  be  moved  forward 
and  back  and  controls  the  elevation  rudders  EE.  When  pushed 
forward,  the  rudders  are  turned  down  and  the  machine  descends ; 
when  the  lever  is  pulled  back,  the  machine  ascends. 

The  lever  in  the  aviator's  left  hand  LL  is  moved  from  side  to 
side  and  with  it  moves  the  axle  and  drum  to  which  the  cross  arm 
wires  are  attached,  shown  on  the  edge  of  the  left  upper  side  of 
the  skiff-like  body. 

The  wires  lead  from  this  drum  down  to  a  crossarm  which  is 
rigidly  fixed  to  a  second  drum  to  which  the  actual  warping  wires 


/ 
-f' 


THE  HANRIOT  CONTROLLING  SYSTEM 

are  attached.  If  the  right  side  sinks,  then  to  correct  the  ec[ui- 
librium  the  lever  LL  is  moved  over  to  the  left.  This  causes  the 
lower  drum  and  crossarm  to  move  counter  clockwise,  and  by  pull- 
ing on  the  wire  leading  to  the  right  wing,  causes  its  incidence  and 
therefore  its  lift  to  be  increased. 

8.  WRIGHT 

The  new  Wright  controlling  system,  see  p.  288,  is  at  once  the 
most  complicated  and  the  simplest  of  all  the  different  systems  used. 
The  operation  is  simple  enough.  The  structure,  however,  is  quite 
intricate. 


288 


MONOPLANES    AND   BIPLANES 


The  system  shown  below  is  one  of  many  Wright  systems,. 
there  being  several  modifications,  depending  primarily  on  whether 
the  operator  elevates  with  his  right  hand  as  Wilbur  Wright,  or 
with  his  left  hand  as  Orville  Wright,  and  Brookins.  In  some 
instances  all  the  wheels  and  chains  are  at  one  side,  and  the  motion 
of  the  outside  lever  carried  through  by  an  inner  tube  or  rod. 


THE  WRIGHT  CONTROLLING  SYSTEM 

The  operation  of  the  elevation  rudder  E  by  the  lever  EL,  con- 
sists merely  in  pushing  the  lever  forward  for  descent,  and  pulling 
it  in  for  ascent. 

The  lever  marked  LL  operates  the  rudder  and  warping  com- 
bined by  a  front  and  back  motion.  This  lever  has  a  movable  han- 
dle which  permits  of  its  being  "broken,"  i.  e. :  the  handle  moved 


MONOPLANES    AND    BIPLANES 


389 


side  to  side.      To  "break"  a  Wright  warping  and  rudder  lever  is 
merely  to  operate  this  handle. 

As  already  stated,  a  front  to  back  motion  of  this  lever  causes 
both  the  warping  and  the  rudders  KR  to  be  operated  in  unison. 


THE  MACHINE  FOR  THE  INSTRUCTION  OF  AVIATORS  AT  THE 
ANTOINETTE  SCHOOL 

The  instructor  throws  the  seat  in  various  directions  and  the 
pupil,  by  operating  the  controls,  learns  not  only  to  correct 
any  change  of  position,  but  is  able,  after  much  practice, 
to  catch  and  prevent  any  disturbing  movement. 

But  the  chains  and  drums  of  these  two  motions  although  both 
mounted  on  the  same  shaft,  are  not  connected.  Therefore  the 
smaller  one  governing  the  rudder  ER  can  be  moved  independently 
of  the  other  by  "breaking"  the  lever. 

If  it  was  desired  for  example  to  perform  a  very  sharp  turn  to 


290  MONOPLANES    AND    BIPLANES 

the  left  the  operation  would  be  as  follows.  The  machine  is  first 
inclined  upward  on  the  right  by  pushing  out  on  lever  LL.  This 
pulls  in  wire  "to  right  plane"  and  causes  that  side  to  be  warped 
down  and  therefore  to  rise.  Pushing  out  on  lever  LL  also  causes 
the  rudder  RR  to  be  turned  to  the  left  (for  a  left  turn) .  The  ma- 
chine has  now  acquired  the  requisite  centrifugal  action  and  the 
lever  LL  is  brought  back,  but  at  the  same  time  it  is  "broken"  forc- 
ibly over  to  the  left,  thus  turning  the  rudder  RR  alone  and  causing 
the  machine  to  "skew"  around  almost  on  end.  If  a  spiral  "cork- 
screw" dip  were  to  be  executed  the  same  process  would  be  em- 
ployed, except  that  in  the  beginning  the  elevator  would  be  turned 
down  for  a  dive  to  give  momentum  to  the  machine,  and  bring  the 
rudder  and  warping  action  into  play  more  strongly. 

These  are  the  principal  controlling  systems,  and  they  differ 
in  degrees  of  instinctiveness  and  grouping  in  which  the  various 
motions  are  united. 

The  main  questions  in  any  controlling  system  and  the  ones  that 
can  really  be  settled  only  by  individual  preference  are: 

(1)  Whether  the  control  should  be  direct  or  indirect,  whether 
the  motion  of  the  control  should  be  in  the  direction  in  which  the 
machine  is  to  react  or  opposite  to  it. 

(2)  Whether  the  different  controls  are  to  be  united  at   one 
place,  as  on  the  Breguet,  or  divided  separately,  as  on  the  Antoi- 
nette. 

No  general  advantages  of  any  one  system  over  any  other  can  be 
laid  down  because,  of  course,  what  appears  instinctive  to  one  man, 
may  appear  very  difficult  to  another. 


CHAPTER  XIV. 

ACCIDENTS 

"La  prudence  est  la  vertu  des  aviateurs." 
F  L  Paulhan. 

Railroads,  automobiles  and  in  fact  all  forms  of  locomotion  have 
their  victims.  Great  mine  disasters,  industrial  catastrophies,  fires 
and  explosions  claim  their  toll  of  human  life.  But  so  small  does 
the  proportion  of  fatalities  appear  to  be,  that  we  do  not  for  a 
moment  consider  any  of  these  means  of  locomotion  or  lines  of 
human  endeavor  as  really. dangerous. 

Yet  the  many  recent  tragedies  in  aviation  are  so  graphically  por- 
trayed and  so  absorbingly  dwelt  upon  by  the  press  and  the  public  in 
general  that  the  realization  of  the  negligence  on  the  part  of  the 
very  aviators  who  are  killed  is  often  obscured.  The  hasty  judgment 
of  the  all  too  credulous  world  is  passed,  that  it  is  the  aeroplane 
itself  that  is  fundamentally  dangerous. 

As  a  matter  of  fact,  however,  if  the  great  care  and  judgment 
that  is  necessary  be  properly  exercised,  aviation  is  as  safe  if  not 
safer  than  automobiling.  But  in  the  ability  to  execute  this  care 
and  judgment  lies  the  striking  difference  between  Wilbur  Wright, 
Curtiss,  Bleriot,  Farman  and  the  other  aviators  of  the  "old  school" 
to  whom  accidents  rarely  if  ever  happen,  and  the  increasing  group 
of  reckless  and  untutored  "daredevils,"  who  perform  their  highly 
dangerous  spirals  and  volplanes  in  almost  impossible  weather,  and 
who  in  the  end  usually  suffer  the  tragic  death  that  is  awaiting 
them. 

It  is  as  absurd  for  an  aeroplane  to  be  taken  out  and  flown 
under  weather  conditions  peculiarly  hazardous  to  it  alone,  as  it  is 
for  a  sailing  boat  to  set  out  full  sail  into  the  teeth  of  a  hurricane. 

Almost  every  summer  in  the  vicinity  of  New  York  there  occur 
high  and  unexpected  windstorms,  and  the  next  day  the  newspapers 
invariably  report  the  loss  in  human  life  -in  drowning  from  over- 


292 


MOXOPLANES    AND    BIPLANES 


turned  sailing  craft  as  anywhere  between  10  and  30  victims.  It 
is  not  every  day,  by  any  means,  that  sailing  boats  can  be  navigated 
in  safety  and  the  prudent  mariner  recognizes  this  and  risks  neither 
himself  nor  his  craft.  It  is  infinitely  more  important  to  consider 


A  LIFE  PRESERVING  GARMENT  FOR  AVIATORS.  WHICH  FORMS  INTO 
A  PARACHUTE  ON  FALLING. 

the  conditions  of  the  atmosphere  in  aviation.  And  yet,  by  the 
novices  they  are  almost  ignored.  Flying  is  indulged  in,  gener- 
ally, both  here  and  abroad,  in  wind  conditions  that  are  prohibitive 
to  safety  and  in  almost  every  case  accidents  can  be  traced  directly 
to  this  source. 

Laffont  and  Pola,  Hoxsey  and  Moisant  are  but  a  few  of  the 


MONOPLANES    AND   BIPLANES  293 

victims  of  their  own  folly  in  daring  to  venture  as  they  did  into  the 
swirls  and  turmoils  of  the  upper  air,  the  existence  of  which  experi- 
enced aviators  warned  them  of. 

All  these  catastrophes  have  a  cause,  but  that  which  stupefies 
everyone  is  that  in  many  cases  the  cause  remains  unknown.  The 
fatal  plunge  is  often  laid  to  a  broken  wire,  a  splintered  spar  and 
finally  to  a  collapsed  wing;  but  a  moment  of  thoughtful  investi- 
gation shows  that  all  these  are  not  the  causes  at  all.  They  are 
merely  the  effects.  Some  peculiar  combination  of  forces  and  pres- 
sures has  overstrained  the  part  and  caused  its  breakage.  In  many 


r*t 
$»£ 


A  WRECK  OF  A  BL£RIOT 

On  Sunday,  Oct.  23rd,  1910,  at  Belmont  Park,  Moisant  attempted  to  fly  his  Bleriot 
XI  2  bis  in  a  gale.     The  machine  capsized  with  the  result  here  depicted. 

cases  the  fall  takes  place  without  any  breakage  at  all  and  can 
only  be  due  to  a  loss  of  equilibrium  caused  by  the  disturbing 
forces. 

Whatever  the  cause,  one  fact  stands  out  with  enormous  signifi- 
cance : 

Over  80  per  cent,  of  the  accidents  that  have  taken  place  have 
occurred  in  conditions  of  wind  that  were  easily  recognized  as 
•dangerous. 

There  have  been  such  conflicting  reports  about  many  of  the 
.accidents  that  it  is  almost  impossible  to  describe  and  explain  them. 


294 


MONOPLANES   AND   BIPLANES 


There  are  at  present,  however,  nine  distinct  ways  in  which  acci- 
dents are  observed  to  take  place. 

1.  The  aviator  appears  to  lose  control;  the  aeroplane  begins  to 
sway  and  dive  uncertainly,   and  finally  it  lands  heavily   and   is 
smashed  with  more  or  less  fatal  results  to  its  driver.     This  has 
been  observed  in  all  kinds  of  weather,  both  calm  and  windy. 

2.  The  aeroplane  collides  with  obstructions  either  when  land- 
ing, starting  or  in  mid-air. 

3.  The  aeroplane  appears  to  land  too  heavily  and  is  in  conse- 
quence more  or  less  totally  wrecked. 


At  Nice,  April  17th,  1910,  Chavez  on  his  Farman  was  suddenly  deprived  of  fuel. 
The    biplane    lost   headway   and    landed   heavily    on   the    beach,    the    chassis 
being  completely  smashed. 

4.  In  making  a  turn  the  equilibrium  appears  to  be  lost,  and 
the  machine  falls  in  various  ways.     This  is  seen  to  happen  most 
frequently  to  novices,  especially  on  Bleriot-Gnomes. 

5.  The  aeroplane,  due  to  sudden  stoppage  of  the  motor,  loses 
headway  and  falls  tail  on  to  the  ground. 

6.  The  aeroplane  appears  to  break  apart  in  some  way  in  mid- 
air while  in  full  horizontal  flight,  or  a  broken  spar  or  wire  causes 
loss  of  balance. 


MONOPLANES    AND    BIPLANES  295 

7.  While  in  ordinary  motor  flight  the  aeroplane  is  seen  to  pitch 
forward  suddenly  and  dive  head  on  down  to  the  ground,  appearing 
to  have  lost  its  support,  although  no  breakage  is  observed. 

8.  A  similar  sudden  plunge  is  frequently  seen  to  occur  when  the 
aeroplane  is  in  volplane. 

9.  At  the  instant  when,  after  a  long  downward  dip,  the  aero- 
plane is  turned  up  in  order  to  land  tangentially,  the  wings  appear 
to  break  loose  and  fold  up  overhead  with  a  terrific  force. 


THE  DAMAGE  DONE  TO  AN  ANTOINETTE  BY  A  HEAVY  "HEAD-ON" 
LANDING 

The  propeller  and  one  wheel  are  damaged.     The  planes  and 
frame  are  intact. 

Accidents  that  occur  in  the  first  six  ways  are  easily  explainable, 
and  as  easily  avoidable  by  the  exercise  of  skill  and  care.  Acci- 
dents represented  by  ways  7,  8  and  9,  however,  are  extremely  hard 
to  explain  and  are  causing  aviators,  constructors,  and  experts  alike 
a  great  deal  of  worry.  It  is  an  especial  object  of  this  chapter,  to 
present  two  very  plausible  explanations  of  these  kinds  of  acci- 
dents, that,  if  recognized  as  true,  will  lead  to  their  practical  elimi- 
nation. 

I. 

That  it  is  possible  for  aviators  themselves  to  become  physically 
unable  to  control  their  machines,  especially  after  a  rapid  descent 
from  a  high  altitude  is  now  believed  to  be  a  fact.  Labouchere 


296 


MOXOPLANES    AND    BIPLANES 


has  described  at  great  length  the  feeling  of  extreme  nausea  that 
came  over  him  when  about  to  return  from  a  high  flight.  Morane 
says  that  on  one  occasion  after  turning  off  the  motor  and  starting 
to  swoop  down  from  a  high  altitude,  he  became  so  dizzy  and  felt  so 
ill  that  he  lost  completely  the  control  of  the  machine,  and  was 
saved  only  by  fortunate  circumstances.  Drexel  and  Latham  also 
testify  to  this  effect  of  altitude  and  consider  it  a  form  of  "mountain 


A  WRECKED  ANTOINETTE  AT  HELIOPOJ  is,  EGYPT,  IN  1910 

sickness/-  It  is  said  that  Chavez,  at  the  end  of  his  great  trans- 
Alpine  trip,  was  affected  by  this  dizziness,  and  that  his  fall  was 
due  primarily  to  loss  of  control,  even  though  the  wings  were  seen 
to  break  in  mid-air. 

Many  eminent  French  physicians,  including  Prof.  Moulinier, 
have  investigated  the  effect  of  high  altitude  on  the  blood  and 
heart  action  of  aviators,  and  definitely  conclude  that  in  addition 
to  the  usual  harmful  effects  of  passage  from  a  low  to  a  high  alti- 
tude, the  sudden  return  from  the  high  altitude  to  the  ground, 


MONOPLANES    AND    BIPLANES 


397 


which  in  many  cases  takes  but  a  few  moments,  has  a  very  serious 
effect,  that  can  be  withstood  for  a  short  time  only  by  men  with  ex- 
tremely sound  hearts  and  subtle  arteries. 

Dizziness,  however,  does  not  come  from  altitude  alone.  Orville 
Wright  and  many  French  aviators  have  been  troubled  by  a  physi- 
cal effect  of  this  kind  as  a  result  of  making  numerous  short,  sharp 
turns,  as  Jolmstone  and  Hoxsey  were  accustomed  to  do,  and  many 


WRECK  OF  A   VOISIN  AT  RHEIMS,   1POO 

Tho   picture  indicates  that   imperfect  lateral  stability   probably  caused 
the  accident. 

novices  who  are  likely  to  get  "seasick"  find  that  they  become  ill 
on  a  windy  day  when  the  machine  pitches  a  great  deal. 

The  recent  fatal  accident  to  Capt.  Madiot,  who  was  killed  on 
Oct.  23,  1910,  at  Douai  on  a  Breguet  biplane,  and  that  to  Lieut. 
Willi  Mente,  who  was  killed  at  Magdeburg  two  days  later  on  a  Ger- 
man Wright,  appear  to  have  been  due  to  loss  of  control  alone.  In 
both  cases  the  aviators  were  observed  to  hesitate  and  fly  uncertainly, 
and  when  the  machines  finally  reached  the  ground,  all  wire  stays, 
etc.,  were  found  intact. 


298  MONOPLANES    AND    BIPLANES 

In  many  cases  where  an  aviator  is  affected  by  some  form  of 
heart  failure,  death  has  occurred  before  the  ground  was  reached. 
Tliis  is  supposed  by  many  to  have  been  the  real  manner  in  which 
Hoxsey  died. 

There  seems  now  little  doubt  that  in  many  cases,  especially 
after  a  long  run,  an  aviator  is  likely  to  become  tired  and  nervous 
and  finally  so  affected  by  vertigo  and  possibly  fainting,,  that  he  loses 
his  presence  of  mind,  mixes  up  the  controls  and  falls. 


WRECK  OF  THE  BL^RIOT  SO  HORSE-POWER  MONOPLANE  AT 
RHEIMS,  1909 

This  was  due  to  fire,  as  great  a  danger  to  aeroplanes  as  to 
other  craft.  Note  the  motor  and  the  charred  propeller. 
M.  Bleriot  was  bruised  and  burned. 

For  all  ordinary  cases  of  this  kind,  the  presence  of  two  aviators 
capable  of  relieving  each  other  would  be  a  wise  precaution. 

To  avoid  the  altitude  effects,  men  with  weak  hearts  should 
never  fly  above  1000  feet,  and  the  quick  downward  swoops  from 
high  altitudes  that  have  so  entertained  the  public  of  late  should  be 
discouraged. 

In  accidents   due   apparently  to  loss  of  control,   there   is,   of 


MONOPLANES    AND    BIPLANES  299 

course,,  the  possibility  of  a  breakage  in  the  controlling  system  itself. 
A  wire  may  snap  or  a  rudder  become  jammed  with  very  serious 
consequences.  Such  care  is  taken,  however,  in  the  construction  of 
most  machines,  and  aviators  themselves  usually  inspect  their  ma- 
chines so  thoroughly,  that  accidents  due  to  this  source  are  reason- 
ably avoidable,  and  when  they  do  occur  indicate  only  negligence. 


THE  1909  BREGUET  BIPLANE  JUST  AS  IT  STRUCK  THE  GROUND 
HEAD-ON  AT  RHEIMS 

M.  Breguet,  who  can  be  seen  plunging  from  his  seat,  escaped 
miraculously  without  any  serious  injuries.  If  he  had  been 
sitting  in  front  of  the  motor  he  probably  would  have  been 

2. 

Collisions  of  aeroplanes,  with  obstacles  when  landing,  starting 
or  in  full  flight,  are  of  frequent  occurrence,  and  two  aeroplanes 
have  been  known  to  collide  in  mid-air,  but  the  results  of  such 
accidents  are  rarely  fatal,  although  the  machines  may  be  totally 
wrecked.  They  are  as  avoidable  as  collisions  in  any  other  form  of 
locomotion,  and  it  is  certain  that  the  collision  of  two  aeroplanes 
headed  towards  each  other  in  mid-air  is  much  less  likely  than  that 


300 


MONOPLANES    AND    BIPLANES 


•=- 

~~  y 


s  ^ 
c:-*-> 
w^3 


•0.3 
•§3 


^ 


II 


- 


ss 


MOXOPLAXES    AXD    BIPLANES  301 

of  two  automobiles  in  like  circumstances  on  a  road,  because  of 
the  greater  freedom  of  movement  that  is  available. 

The  tragic  accident  to  Hauvette-Michelin  at  Lyon  on  May  13, 
1910.  was  said  to  be  due  to  the  fact  that  his  Antoinette  collided 
with  a  pylon,  and  many  other  such  accidents  have  happened,  though 
not  always  with  as  serious  consequences.  They  point  merely  to  the 
importance  of  having  a  large,  clear  ground  to  start  from  and  land 
on,  a  provision  that  is  as  necessary  for  aeroplanes  as  the  Ambrose 
Channel  is  for  the  "Mauretania." 

3. 

That  many  serious  breakages  occur  from  landing  too  heavily 
is  merely  to  say  that  the  effect  of  a  fall  is  collision  with  the  earth. 
If  the  aeroplane  is  too  heavily  loaded  and  its  speed  not  high  enough 
to  give  a  "tangential  landing"  then  the  shock  of  impact  with  the 
ground  may  do  a  great  deal  of  damage  from  the  breakage  of  a 
chassis  to  the  complete  smashing  of  the  machine;  but  it  has  been 
actually  found  in  practice  that  if  the  aviator  is  strapped  in  and 
the  aeroplane  well  designed,  he  will  suffer  only  a  few  cuts  and 
bruises. 

The  wreck  that  happened  to  Brookins  at  Belmont  Park  when 
about  to  start  in  the  Gordon  Bennett  was  due  entirely  to  the  fact 
that  the  machine  had  not  enough  velocity  to  support  the  heavy 
loading  and  the  chassis  was  too  weak  to  stand  the  shock  of  landing. 
Had  the  machine  had  a  lighter  loading  and  a  stronger  chassis,  the 
sudden  stoppage  of  the  motor  would  probably  have  had  no  serious 
effect. 

The  avoidance  of  accidents  of  this  kind  lies  in  doing  away  with 
the  heavy  loading,  or  else  in  landing  at  a  high  enough  velocity  by 
keeping  the  motor  running,  as  is  done  with  many  of  the  high- 
powered  Bleriots. 

4. 

Turning  in  an  aeroplane  and  especially  in  one  fitted  with  a 
Gnome  motor,  requires  a  great  deal  of  skill  and  much  practice.  It 
is  said  abroad  that  over  75  per  cent,  of  the  accidents  that  happen 
to  novices  are  due  to  a  sudden  fall  as  a  result  of  a  false  manoeuvre 
in  turning. 


302 


MONOPLANES    AND    BIPLANES 


Whatever  the  nature  of  these  accidents,  however,  they  are  avoid- 
able only  by  the  acquirement  and  constant  exercise  of  that  ordi- 
nary amount  of  skill  that  the  obtaining  of  a  pilot's  license  is  sup- 
posed to  require. 

5. 

Aeroplanes,  especially  those  with  large  lifting  tails  like  the 
Farman,  are  likely  to  lose  headway  when  the  motor  suddenly  stops. 


THE  RESULT  OF  Loss  or  BALANCE  DUE  TO  RISKY  FLYING 
The  wreck  of  Lefebvre's  Wright  machine. 

Whether  this  results  in  a  serious  fall  or  not  depends  altogether  on 
the  skill  of  the  aviator.  With  a  fair  amount  of  presence  of  mind 
and  a  high  enough  altitude  the  sudden  breaking  down  of  the  motor 
need  have  no  serious  consequences.  If  it  is  very  gusty,  however, 
other  effects  may  take  place  and  complicate  the  descent. 

The  habit  of  many  aviators,  notably  Paulhan  and  Leblanc,  of 
flying  "tail  high"  is  not  so  much  a  matter  of  gaining  speed  by  a 
reduction  of  the  angle  of  incidence,  as  it  is  a  measure  of  safety  that 


MONOPLANES    AXD   BIPLANE- 


303 


in  case  the  motor  stops  suddenly,  the  machine  will  at  once  tend 
to  dive.  Fortunately  accidents  from  loss  of  headway  are  becoming 
more  and  more  rare,  but  they  still  constitute  a  large  percentage. 

Losses  of  headway,  due  to  the  breakage  of  any  tail  piece  or  the 
jamming  of  the  elevation  rudder  in  the  ascent  position  are  like- 
wise rare,  although  they  are  likely  to  happen  and  are  avoidable 
only  by  structural  perfection  and  strength. 


A  WRECKED  FARMAN  BIPLANE  AT  BROOKLANDS 

Evidently  the  surest  and  safest  provision  against  motor  troubles 
is  to  equip  the  aeroplanes  with  two  motors,  each  alone  powerful 
enough  to  keep  the  machine  in  flight. 

One  of  the  most  progressive  indications  of  the  appreciation  of 
the  importance  and  value  of  this  disposition  is  the  prize  of  $15,000 
that  is  generously  offered  through  the  Scientific  American  by  Ed- 
win Gould,  to  be  awarded  for  the  best  performance  of  an  aero- 
plane equipped  with  two  separate  power  plants. 


304 


MONOPLANES   AND   BIPLANES 


f 

k/ 


HOXSEY  PLUNGING  TO  His  DEATH  AT  Los  ANGELES 


MONOPLANES   AXD   BIPLANES  305 

6. 

Many  accidents,  notably  those  to  Delagrange  and  LeBlon,  were 
clue  to  so  great  a  weakness  in  the  apparatus  that  the  increased  pres- 
sure due  to  an  ordinary  turn,  a  passage  between  gusts  or  a  gyro- 
scopic effect,  caused  a  breakage  of  the  wings.  An  aeroplane  must 
be  designed  to  stand  much  higher  pressures  than  those  alone  neces- 
sary for  support.  The  air  is  very  variable,  and  even  on  a  relatively 
calm  day  there  are  likely  to  be  "holes  in  the  air/'  and  the  pass- 
age of  an  aeroplane  through  these  regions  causes  conditions  of 
pressure  that  must  be  resisted  by  additional  strength  in  the  ma- 
chine. Practically  all  the  breakages  that  occur  in  mid-air  are  due 
to  insufficient  strength  to  resist  the  variable  air  pressures  that  are 
met,  or  the  peculiar  and  sudden  forces  caused  by  the  gyroscopic 
action  of  large  rotating  motors.  Only  the  strongest  machines  can 
be  flown  with  safety  on  a  windy  day. 

The  accident  to  Rolls  appears  to  have  been  due  entirely  to  struc- 
tural weakness.  Rolls  was  flying  a  French  Wright  biplane,  to 
which  a  rear  horizontal  surface  had  been  added.  But  the  spars 
designed  to  hold  this  surface  were  much  too  weak  and  they  snapped 
when  strained  by  a  sudden  gust. 

Sommer,  Farman,  Paulhan  and  Tellier  are  but  a  few  of  the 
French  constructors  who  fully  realizing  the  great  strains  an  aero- 
plane is  put  to,  are  bending  all  their  efforts  to  obtain  a  great 
strength  and  solidity  of  structure.  Aeroplanes  must  be  carefully 
designed  and  calculated  with  a  large  co-efficient  of  safety. 

There  are  innumerable  machines  flying  to-day  where  not  only 
no  co-efficient  of  safety  exists  but  where  the  materials  are  con- 
stantly worked  at  their  elastic  limit.  The  fatigue  of  materials 
appears  to  be  ignored,  and  it  seems  profitable  to  do  so — until  the 
fatal  breakage. 

Materials,  whether  wood  or  steel,  are  altered  after  a  time,  by 
oxidation,  changes  in  temperature  and  repeated  vibration.  Glued 
joints  are  at  the  mercy  of  humidity,  as  is  the  tightness  and 
strength  with  which  the  plane  covering  fits  to  the  frame.  Metal 
pieces  are  greatly  affected  by  a  combination  of  magnetic  phenom- 
ena, changes  of  temperature,  and  repeated  vibration  until  after 


336  MONOPLANES    AND    BIPLANES 

many  million  such  vibrations  the  metal  undergoes  an  allotropic 
transformation,  or  passes  from  the  fibrous  to  the  dangerous  crystal- 
line state.  This  is  recognized  in  railroading  practice,  and  even 
though  no  breakages  actually  occur,  the  vibrating  parts  of  locomo- 


A  SNAPSHOT  or  THE  TEARING  AWAY  OF  THE  WINGS  OF  THE  ANTOINETTE  CARRY- 
ING LAFFONT  AND  POLA,  AN  EXCELLENT  EXAMPLE  OF 
THE  EFFECT  OF  CENTRIPETAL  FORCE 

Note  that  the  rear  elevation  rudder  was  turned  up,  i.  e.,  the  machine  was  about 
to  be  brought  back  to  the  horizontal.     The  propeller  is  in  motion. 

tives  and  cars  are  always  replaced  after  they  have  run  a  certain  al- 
lotted number  of  miles.  It  would  be  wise  to  adopt  this  practice 
in  aviation. 

The  number  of  aeroplanes  that  are  built  and  flown  in  which  the 


, 

MONOPLANES    AND    BIPLANES  307 

construction  is  weak  and  unsafe  is  fortunately  rapidly  decreasing. 
But  there  still  exist  aeroplanes  of  so  poor  a  structure  that  to  at- 
tempt to  fly  in  them  is,  to  express  it  mildly,  a  very  risky  matter.  At 
the  recent  exhibition  of  aeroplanes  in  New  York  City  the  author 
had  occasion  to  inspect  a  biplane  that  had  been  constructed  by  an 
American  firm  for  a  well-known  English  aviator,  and  found  that 
one  of  the  wooden  spars,  leading  out  to  the  rear  Farman  type  sta- 
bilizing cell,  had  a  large  knot-hole  about  at  the  center,  where  the 
bending  moment  was  greatest,  that  reduced  the  effective  cross  sec- 
tion of  the  member  to  almost  one-fourth  of  what  it  was  supposed  to 
be. 

Accidents  in  mid-air  to  aeroplanes  of  such  a  structure  are  to  be 
expected. 

7  and  8. 

The  sudden  dives  that  are  frequently  observed  and  that  the 
aviators  who  experience  them  are  positive  do  not  result  from  any 
false  rudder  movement  are  indeed  hard  to  explain.  Whether  in 
motor  flight  or  in  gliding  flight,  aeroplanes  are  again  and  again 
seen  to  pitch  forward  suddenly  and  dive  towards  the  ground,  as  if 
the  supporting  power  were  annulled.  Frequently  aviators  are  able 
to  correct  this  sudden  plunge,  but  unfortunately  they  are  some- 
times taken  unawares  and  a  fatal  drop  to  the  ground  results.  One 
fact,  however,  stands  out  quite  clearly,  and  that  is  that  accidents 
of  this  kind  usually  occur  in  a  gusty  wind. 

To  upset  suddenly  a  mass  of  the  size  of  an  aeroplane  requires 
a  considerable  force.  The  gyroscopic  force  of  a  rotating  Gnome 
must  certainly  be  appreciable,  but  it  is  an  open  question  whether 
it  is  considerable  enough  to  jerk  the  aeroplane  down  in  the  man- 
ner observed.  The  effect  of  this  gyroscopic  action  would  more  like- 
ly be  a  straining  and  breakage  in  the  framework  itself,  and  mani- 
fest itself  as  an  internal  force.  To  upset  the  aeroplane,,  however, 
some  very  large  external  force  must  act. 

On  an  aeroplane  in  flight  there  is  no  source  of  external  force 
other  than  the  pressure  of  "the  air  itself. 

In  Part  I.,  Chapter  V.,  the  characteristics  of  the  movement  of 
the  center  of  pressure  on  an  aeroplane  surface  are  clearly  given.  It 


308  MONOPLANES    AND    BIPLANES 

is  definitely  known,  now,  that  when  an  aeroplane  is  suddenly 
moved  from  a  low  angle  of  incidence  to  a  still  lower  one,  the  cen- 
ter of  action  of  the  supporting  force  moves  rapidly  to  the  rear.  If 
this  movement  is  not  at  once  counteracted  by  the  elevation  rudder, 
the  aeroplane  will  be  thrown  out  of  equilibrium,  because  the  sup- 
porting force  will  act  in  back  of  the  center  of  gravity.  This  will 
cause  a  rotating  force  equal  to  the  weight  of  the  aeroplane  acting 


CHAVEZ  STARTING  FROM  BRIGUE  FOR  His  TRANS-ALPINE  FLIGHT 


f 

MONOPLANES    AND    BIPLANES  309 

with,  a  lever  arm  that  is  the  distance  between  the  point  of  action  ot 
the  supporting  force  (c.  p.)  and  the  center  of  gravity  (c.  g.).  This 
force  will  turn  the  rear  of  the  machine  up  and  the  front  down, 
and  cause  the  aeroplane  to  dive.,  and  will  do  so  as  suddenly  and  in 
as  great  measure  as  the  angle  of  incidence  is  changed.  The  lower 
the  angle  and  the  greater  its  sudden  additional  lowering,  the 
greater  will  be  the  movement  of  the  c.  p.  and  consequently  the 
more  powerful  the  disturbing  force.  The  cause  of  this  movement 
is  the  pressure  of  the  wind  striking  the  surface  of  the  plane  and 
jerking  it  down  in  front. 

It  is  known  that  in  a  high  and  gusty  wind  the  direction  of  the 
wind  changes  often  and  very  suddenly.  Assuming  then  that  we 
have  an  aeroplane  moving  at  an  angle  of  incidence  of  5  degrees  in 
a  horizontal  region  of  air,  if  in  the  nature  of  a  sudden  gust,  this 
air  region  changes  to  one  that  is  moving  downward  at  an  angle 
of  5  degrees  below  the  horizontal,  then  the  angle  of  incidence  of 
the  aeroplane  will  as  suddenly  drop  from  5  degrees  to  0  degrees. 

It  must  be  borne  in  mind  here  that  the  angle  of  incidence  is 
the  angle  between  the  chord  of  the  plane  and  the  relative  air  cur- 
rent, and  that  the  velocity  of  the  wind  itself  is  immaterial,  since  it 
only  affects  the  motion  of  the  aeroplane  with  respect  to  the  earth, 
the  aeroplane  moving  through  the  air  at  its  ordinary  velocity. 

In  this  sudden  drop  from  an  incidence  of  5  degrees  to  one  of 
0  degrees,  the  c.  p.  would  jump  back  about  2  to  4  feet  on  a  large 
plane,  if  the  experimental  data  and  facts  upon  which  this  is  based 
are  at  all  reliable.  We  then  have  a  force  equal  to  the  weight  of 
the  machine,  suddenly  applied  with  this  large  lever  arm.  The  nat- 
ural consequence,  if  this  force  is  permitted  to  act  for  a  fraction 
of  time,  is  the  destruction  of  the  balance  and  a  dive  downward. 
Incidentally  it  may  be  pointed  out  that  if  the  wind  were  in 
the  rear  of  the  aeroplane,  a  sudden  upward  gust  would  have  the 
same  effect. 

If  the  aviator  is  taken  unawares,  and  the  change  in  wind  di- 
rection very  pronounced,  the  machine  will  suddenly  dive  down- 
ward and  plunge  to  the  ground.  On  a  Wright  machine  the  effect 
would  be  to  throw  the  aviator  forward  on  the  levers  and  thus  fur- 


310 


MONOPLANES    AND    BIPLANES 


HAMILTON  ON  His  CURTISS  BIPLANE,  TRAVELLING  FROM 
YORK  TO  PHILADELPHIA,  JUNE  13TH,  191 

The  semaphores  indicate  the  passage  of  the  train  from  which 
this  photograph  was  taken.  Great  steadiness  was  displayed 
the  entire  trip. 


MONOPLANES    AXD    BIPLANES 


311 


ther  accentuate  the  dive — viz.:  Hoxsey.  On  a  Bleriot  it  would 
throw  him  on  the  cloche,  or  if  great  enough  pitch  him  headlong 
out  of  his  seat — viz. :  Moisant. 

9. 

There  is  one  other  type  of  accident  that  has  puzzled  aviators  as 
much  as  the  sudden  dives — that  is  the  collapsing  of  the  planes 
of  a  seemingly  strong  machine  at  the  moment  when  it  is  recovering 


WILBUR  WRIGHT  AT  ROME 


(See 


from  a  long  downward  dip,  in  order  to  land  tangentially. 
Xo.  1  in  the  diagram  p.  314.) 

Probably  no  other  kind  of  accident  is  so  unexpected  and  appar- 
ently so  impossible  of  explanation.  Again  and  again,  Chavez, 
Blanchard,  Laffont  and  Pola,  being  only  a  few  of  the  victims,  the 
aeroplane  when  just  about  to  turn  the  arc  with  center  at  A  (see 
diagram  on  p.  314)  is  seen  to  quiver  for  a  moment  and  then  the 
planes  are  torn  away  upward  from  the  body  and  the  entire  mass 
crashes  to  the  ground.  No  other  kind  of  accident  is  so  relentless  in 
its  result. 


312 


MONOPLANES    AND    BIPLANES 


CUBTISS  PASSING  STORM  KING  ON  His  HISTORICAL  ALBANY 
TO  NEW  YORK  FLIGHT,  MAY  .29ra,  1910 

Not  an  accident  occurred  on  this  skillfully  executed  trip. 


6  •» 

1 ' 

MONOPLANES    AND    BIPLANES  313 

An  explanation  is  hard  to  find  and  though  one  is  given  here, 
decision  as  to  its  final  value  is  reserved  until  more  is  learned  on 
this  highly  important  subject. 

The  sudden  breakage  of  the  planes  is  evidently  due  to  an  enor- 
mously sudden  increase  of  pressure  on  them. 

It  is  actually  known  that  accidents  of  this  kind  occur  only  after 
long  and  steep  "djps"  or  after  short  "dips"  on  a  very  windy  day. 

In  the  diagram  on  p.  314:  is  represented  an  aeroplane  making 
a  steep  dip.  At  B  the  aviator  stops  the  motor  and  starts  to  make 
the  dive,  and  when  he  gets  anywhere  within  15  to  150  feet  of  the 
ground,  depending  on  his  "nerve,"  he  suddenly  sets  the  elevation 
rudder  for  ascent,  which  causes  the  machine  to  describe  a  curved 
trajectory  with  center  at  A,  and  a  radius  often  as  small  as  100 
feet.  The  motor  is  then  re-started  and  the  aeroplane  travels 
along  a  little  below  the  horizontal  until  finally  it  lands  "tangen- 
tially"  and  the  public  present  applauds  the  thrilling  perform- 
ance, little  realizing  its  immense  danger.  As  it  dives  from  B  the 
aeroplane  gains  enormously  in  velocity,  depending  altogether,  of 
course,  upon  how  steep  the  dive  is.  If  at  B  the  velocity  is  65  miles 
an  hour  and  the  fall  over  800  feet,  the  velocity  at  A  can  easily 
have  risen  to  70  miles  an  hour,  if  not  more,  and  the  momentum  of 
the  machine  is  large.  The  increased  velocity  makes  the  action 
of  the  rudders  much  stronger,  due  to  the  increased  pressure. 

There  exists  then  at  the  turn  a  mass  of,  let  us  say,  900  pounds, 
'moving  at  70  miles  an  hour,  and  about  to  describe  the  arc  of  a  cir- 
cle with  center  at  A  and  a  radius  possibly  100  feet. 

Any  mass  in  order  to  describe  a  circle  must  be  constrained  to  its 
orbit  by  a  force  acting  towards  the  center  on  the  body  and  from 
the  outer  region  which  is  the  centripetal  force  of  the  familiar 

mv2 

form   • 

r 

Computing  the  centripetal  force  for  this  903  Ib.  aeroplane  de- 
scribing this  orbit,  there  is  obtained  for  it  the  value  of  almost  3,000 
pounds  or  more  than  three  times  the  normal  pressure  on  the  planes. 
It  is  little  wonder  that  they  tear  apart,  since  this  is  acting  up  under 
the  planes  to  hold  the  machine  towards  A. 


31 J: 


MONOPLANES    AND    BIPLANES 


\ 


VJ    " 


MONOPLANES    AND   BIPLANES 


315 


This  enormous  force  is  as  great  in  its  effect  as  if  each  side  of 
the  plane  hit  a  stationary  obstacle  at  this  point.  The  significance 
of  this  centripetal  force  becomes  at  once  apparent.  It  is  interest- 
ing to  note  in  addition  that  accidents  of  this  kind  do  actually 
occur  much  more  frequently  to  monoplanes  than  to  biplanes.  The 
nature  of  the  bracing  explains  this. 


THE  CALM  OF  THE  UPPER  AIR  is  AT  TIMES  SEREXE 
Brookins  at  Indianapolis,  June,  1910. 


316 


MONOPLANES    AND   BIPLANES 


f  I 

MONOPLANES    AND    BIPLANES  317 

In  conclusion  it  may  be  said  that  while  accidents  of  the  first 
six  types  are  fully  recognized  and  therefore  more  and  more  avoid- 
ed, accidents  due  to  the  sudden  shifting  of  the  center  of  pressure 
and  to  the  centripetal  force  when  turning  at  the  bottom  of  a  dip 
are  not  yet  generally  realized  and  every  effort  should  be  bent  to 
their  ultimate  abolition. 

The  remedies  for  these  two  causes  are  clearly  evident  and  cer- 
tainly capable  of  execution.  Two  immensely  important  facts  stand 
out: 

1.  Flying  in  gusty  weather  conditions  is  dangerous. 

2.  Descending  by  means  of  the  long,  steep  "dip"  is  still  more 
dangerous. 

To  avoid  ( 1 )  more  care  should  be  exercised  by  aviators  in  flying, 
when  conditions  are  really  bad. 

r.I  o  avoid  (2)  other  methods  of  descent  indicated  on  p.  314 
should  be  used,  and  the  long  "dip"  should  be  absolutely  prevented 
or  the  strength  of  the  machines  very  greatly  increased. 

Most  of  these  accidents  in  aviation,  therefore,  are  avoidable  if 
flying  in  spirals  and  steep  volplanes  for  the  purpose  of  thrilling 
the  public  is  stopped,  and  if  aviators  acquire  and  use  better  judg- 
ment in  interpreting  the  conditions  of  the  weather. 


318  MONOPLANES   AND   BIPLANES 


DE  LESSEES  CROSSING  THE  CHANNEL  ON  His  BL^RIOT 
XL,  MAY  21ST,  1910 


CHAPTEK  XV. 

THE    VARIABLE     SURFACE    AEROPLANES 

Conditions  of  starting  and  landing  are  the  most  pronounced 
limitations  to  high  speed,  and  it  is  now  becoming  recognized  that 
the  aeroplane  that  is  able  to  fly  slowly  when  near  the  ground  and 
faster  and  faster  in  the  air,  at  the  will  of  the  pilot,  is  to  mark  as 


ELY  ABOUT  TO  ALIGHT  ON  THE   CRUISER   "PENNSYLVANIA,"   IN   SAN   FRANCISCO 

HARBOR,  JAN.,  1911 

great  an  advance  in  aviation  as  did  the  introduction  of  transverse 
control  by  the  Wrights. 

A  simple  means  of  effecting  this  desired  range  of  velocity  is  to 
alter  the  size  of  the  surface  itself.  It  is  easily  demonstrated  from 
the  theory  of  the  aeroplane  (see  Part  I.)  that  as  the  velocity  is 
increased,  the  lifting  pressure  on  the  planes  also  increases  and  to 
so  great  an  extent  that  a  much  smaller  surface  is  required  for  sup- 


320 


MONOPLANES   AND   BIPLANES 


port.  Converse!}7,  if  the  supporting  surface  itself  is  decreased,  the 
resistance  to  motion  becomes  much  less  and  the  velocity  at  once 
increases  to  that  required  for  support  with  the  smaller  plane  area. 
So  that  once  the  aeroplane  is  in  flight,  a  great  increase  of  velocity 
is  obtainable  by  a  gradual  reduction  of  the  surface  area,  and  in 
order  to  decrease  the  speed  to  land  with  safety  all  that  is  necessary 
is  to  spread  out  the  surface  again  to  its  maximum.  The  limiting 
factor  in  this,  other  than  the  amount  of  reduction  possible,  is  the 
pure  head  resistance  of  the  framing,  which,  of  course,  will  not  only 
be  the  same  but  will  be  greatly  increased  by  the  higher  speed. 


ELY'S  CUBTISS  JUST  AFTER  LANDING  ON  THE  CRUISER 

Note  the  single  plane  elevator  and  ailerons  at  the  rear  of  the  main  cell.     Ely, 
later,  took  to  flight  from  the  cruiser's  deck  and  returned  to  his  hangar. 

Actual  computation,  on  an  aeroplane  whose  maximum 
surface  is  300'  square  feet  and  lowest  speed  of  support  50  miles 
an  hour,  shows  that  with  the  same  power  upon  reducing  the  surface 
to  150  square  feet  the  velocity  will  rise  to  over  70  miles  an  hour. 
The  degree  with  which  this  could  actually  be  attained  in  practice 
can  only  be  determined  by  actual  experiment,  but  that  it  is  in 
great  measure  possible  is  hardly  open  to  question. 

Many  means  of  reducing  the  surface  of  an  aeroplane  have  been 
tried.  The  commonest  suggestion  is  to  cause  the  tips  to  turn  back 
horizontally  and  fold  under  the  central  section  of  the  surface,  very 


MOXOPLAXES    AND    B1PLAXES 


321 


much  as  a  bird  folds  its  wings.  Another  method  is  to  have  the 
outer  sections  slide  in  towards  the  center,  thus  greatly  decreasing 
the  span  but  leaving  the  chord  constant.  Most  of  these  methods 


DIAGRAM   ILLUSTRATING  THE   METHOD  OF   "REEFING"   AEROPLANE   SURFACES, 
SUGGESTED  HERE 

are  at  present  found  to  be  structurally  impractical,  and  in  addi- 
tion to  this,  reduction  of  span  alone  is  inadvisable  because  it  re- 
duces the  aspect  ratio  of  the  plane  and  therefore  causes  it  to  be 
less  efficient. 


THE  CURTISS  HYDRO-AEROPLANE  SKIMMING  THE  SURFACE  AT  40  MILES  AX  HOUR 

BEFORE  RISING 

The  simple  boat-like  body  under  the  machine  supports  it  on  the  water,  and  as 
the  speed  increases  it  gradually  rises  entirely  clear  of  the  surface.  This 
new  development  augurs  much  for  the  future.  It  is  over  water  that  the 
aeroplane  will  find  its  greatest  usefulness. 


322 


MONOPLANES   AND   BIPLANES 


A  method  that  is  structurally  feasible  and  that  has  many  ad- 
vantageous features,  is  here  suggested. 

In  the  diagram  on  p.  321  is  shown  a  section  of  the  lower  plane 
of  a  biplane,  illustrating  this  method  of  surface  reduction.  The 
front  section  of  the  plane  between  the  vertical  struts  is  made  double 
surfaced,  a  considerable  clear  space  being  left  between  the  two  sur- 
faces, into  which  the  thin  surface  ABCD  can  slide.  The  large  I 
beam  ribs  are  projected  out  to  the  rear  as  shown,  and  are  so  con- 
structed that  ABCD  slides  or  rolls  in  a  groove  on  each  side. 

In  panel  E,  the  movable  surface  is  shown  extended  to  the  rear. 


SIDE  VIEW  OF  THE  CURTISS  HYDRO-AEROPLANE,   SHOWING   SINGLE  PONTOON 

Note  the  single  plane  elevation  rudder  at  the  front,  the  flap  at  the  rear  of  the 
fan-tail,  and  the  ailerons  on  the  rear  posts  of  the  main  cell.  These  are 
features  of  the  latest  Curtiss  machines. 

If  cable  g  is  pulled,  the  surface  slides  into  the  space  left  for 
it  and  takes  the  position  shown  in  panel  F.  If  cable  h  is  now 
pulled  the  surface  will  again  slide  out.  There  are  innumerable 
ways  in  which  the  control  of  this  motion  may  be  effected,  but  the 
movements  are,  combined  in  such  fashion  that  the  sur- 
faces all  slide  in  and  out  together,  in  an  equal  amount,  unless  an 
unequal  motion  on  opposite  sides  is  to  be  used  for  transverse  con- 
trol, as  it  easily  could  be. 

The  enormous  advantage  of  this  method  of  surface  reduction 


MONOPLANES    AND    BIPLANES 


323 


other  than  its  structural  simplicity,  is  that  in  reducing  the  surface, 
the  span  is  kept  constant  and  the  chord  only  decreased,  so  that  the 
aspect  ratio  is  greatly  increased  and  the  aeroplane  rendered  much 
more  efficient.  The  limit  of  the  reduction  is  a  little  more  than 
half,  as  some  clearance  will  always  be  necessary. 

There  is  one  point,  however,  that  will  need  very  careful  con- 


CURTISS  ix  FLIGHT  AFTEU  RISING  FROM  THE  WATER 

sideration  and  that  is  the  balancing  of  the  movement  of  the  cen- 
ter of  pressure  as  the  reduction  takes  place. 

With  the  present  motors  and  types  of  aeroplane  structure  avail- 
able, there  is  little  doubt  that  by  use  of  this  method,  a  racing  ma- 
chine capable  of  making  85  to  90  miles  an  hour  could  be  designed 
with  ease. 

THE  END. 


INDEX 

PAGE 

ACCIDENTS,    consideration    of   the    various    kinds   and   means   for   their 

prevention 291-317 

Accidents  due  to  physical  inability  of  the  aviator,  discussion  of .  .  .  295-299 

Accidents,    collisions,    discussion    of 299-301 

Accidents  due  to  heavy  landing,  effect  of 301 

Accidents  due  to  lack  of  skill  in  turning 301-302 

Accidents  due  to  sudden  loss  of  motive  power,  consideration  of .  .  .  302—303 

Accidents  due  to  structural  weakness,  consideration  of 305-307 

Accidents  due  to  sudden  movement  of  center  of  pressure,  considera- 
tion  of    307-311 

Accidents,  effect  of  sudden  centripetal  force,  discussion 311-317 

AEROPLANES. 

Aeroplanes,    consideration    of   advantageous-  disposition    of    various 

parts 247-277 

Aeroplanes,  controlling  systems  of — description   of  operation,   etc..  279-290 

Aeroplanes,  definition  of  use  of  terms 92-93 

Aeroplanes,  designs  of,  numerical  examples. 75-89 

Aeroplane   designs — summary   of 88 

Aeroplanes,    efficiency    of,    discussion 270-275 

Aeroplanes,  characteristics  of  flight  of 276 

Aeroplanes,  methods  of  flight,  diagrams  of 314 

Aeroplanes,   loading  on,  table 274 

Aeroplane,    motive    power 85 

Aeroplanes,  pounds  carried  per  horse  power,  table  and  consideration 

of   274-275 

Aeroplanes,   propellers   for 80-88 

Aeroplane,   rudders,   design   of 81-85 

Aeroplanes,  structure  and  size,  discussion  of 209-270 

Aeroplanes,  table  of  speeds  of 277 

Aeroplane  with  variable  surface,  consideration  of  advantage  of.  ...  319-322 

AILERONS,  discussion  of  use  of 260 

AIR. 

Effect,  density   of 17 

Effect  on  density  of  altitude 18 

Effect  on  density  of  state  of  equilibrium 18 

AIR  PRESSURE  ON  PLANE. 

Air    pressure,    calculation    of 31 

Air,   pressure  of  on  unit  plane,   curve 31 

Air   pressure,  action   on   curved  inclined    plane 47 

Air  pressure  on  curved  surface  Lilienthal's  table 49 

Air  pressure,  calculation  of,  on  flat  inclined  plane 40 

Air  pressure  on  flat  inclined  plane,  various  formulae  for 38 

Air,  pressure,  on  inclined  surface,  consideration  of  by  Newton 36 

Air  pressure — on   flat  inclined  plane,  references  to  previous  experi- 
ments   on    43 


326  INDEX 

PACK 

Air   pressure,   lift  and   drift 42 

Air  pressure,  position  of  center  of  action  of 61-66 

AIR   RESISTANCE. 

Air,   resistance  of 17 

Air   resistance   to  trains 28 

Air    resistance,    Constant    K.,    values    as    determined    by    rotating 

apparatus    20 

Air  resistance,   Constant  K.   values  as  determined  by  straight  line 

motion 80 

Air    resistance,    frictional 55-59 

Air  resistance,   frictional,  numerical   examples 56 

Air  resistance,   frictional,  Zahm's  experiments  on 56-50 

Air  resistance,  pressure  on,  effect  of 17 

Air  resistance,  pressure  on  normal  surface,   equation  of 22 

Air  resistance,  pressure  on  flat  inclined  plane,  graphical  representa- 
tion of  various  formulae 30 

Air  resistance,  effect  of  size  of  surface  on,  Kernot 27 

Air  resistance,  effect  of  temperature  on,  Langley 27 

Air  resistance,  variation  of  with  temperature,  Wolff 27 

Air  resistance,   variation  of  with   velocity,   Eiffel 26 

Air  resistance,   Smeaton's  table 23 

Air  resistance,   references  to  previous  works  on 33 

Air  resistance,  experiments  of  Aspinall 28 

Air  resistance,  experiments  of  Bender 24 

Air    resistance,    Beaufoy 22 

Air  resistance,  experiments  of  Cailletet 25 

Air  resistance,  experiments  of  Canovetti 25 

Air  resistance,  experiments  of  Didion 24 

Air  resistance,   experiments  of   Duchemin 24 

Air  resistance,  Eiffel,  experiments  on  air  resistance  in  1905 25 

Air    resistance,    experiments    of    Hagen 24 

Air  resistance,    experiments  of   Hutton 24 

Air  resistance,  experiments  of  Goupil 24 

Air  resistance,  experiments  of  Langley 25 

Air  resistance,  experiments  of  Pole > 25 

Air   resistance,   experiments  of   Poncelet.  . 24 

Air  resistance,  experiments   of  Rayleigh 25 

Air  resistance,   experiments  of   Recknagel 24 

Air   resistance,   experiment  of   Renard 25 

Air  resistance,  experiments  of  Robins 21 

Air   resistance,   experiments   of   Rouse 23 

Air  resistance,   Russell,  experiments  on 28 

Air  resistance,  experiments  of  Stanton 26 

Air  resistance,  experiments  of  Thibault 24 

Air  resistance,  experiments  of  Zahm 26 

Air    resistance,    Zossen    tests 20 

AIE  STREAM. 

Air  stream.  Newton's   idea  of  flow  of 20 

Air  stream,  flow  past  curved  plane  at  high  incidence 45 

Air  stream,  flow  of,  past  flat  plane  at  hi;,rh  incidence 42 

Air  stream,  flow  past  a  curved  plane 51 

Air  stream,  flow  past  a  curved  surface  at  low  angle  of  incidence..  48 


INDEX 

PAGE 

Air  stream,  flow  past  a  normal  surface IS 

Air  stream,  How  past  a  circular  section 24 

Air  stream,   deflection   of  before  normal  surface 32 

Air  stream,  action  of  on   flat  inclined  plane 35-37 

AIR,    weight    of 18 

ALTITUDE,  effect  of  on  density  of  air 18 

ANGLE  OF  INCIDENCE,  air  flow  on  flat  inclined  plane  at  high 42 

Angle  of  incidence,  discussion  of  hest  value  for 264-267 

ANTOINETTE   MONOPLANE,   detailed  description   of 96 

Antoinette  monoplane,  description  of  controlling  system  used  on..  270-281 

Antoinette,  machine  for  the  instruction  of  aviators 289 

ASPECT  RATIO,  effect  of  on  lift  and  drift 72-74 

Aspect   ratio,  discussion   of   effect   of 263-264 

Aspect  ratio,  table  of,  monoplanes  and  biplanes 265 

ASFINALL,  J.  A.   F.,  experiments  on  train   resistance 28 

AUTOMATIC  LATERAL  STABILITY,  discussion  of 260 

AVIATORS,  consideration  of  physical  inability  of 295-299 

BEAUFOY   ON  AIR   RESISTANCE 22 

BIPLANE,  numerical  example  of  design  of 75-89 

BIPLANES,  detailed  descriptions  of  the  prominent  types 161-245 

BLERIOT  TYPES. 

Bleriot  "aero-bus",   monoplane,   detailed   description   of 115-117 

Bleriot  monoplane,  description  of  controlling  system  used  on 281 

Bleriot,    No.    VIII 13 

Bleriot  XL   monoplane,  detailed  description  of 103 

Bleriot  XL  2  bis,  detailed  description  of 108 

Bleriot  XII.   monoplane,  detailed  description  of Ill 

BREGUET  TYPE. 

Brcguet,    biplane,    detailed   description    of 102 

Breguet   biplane,   description  of   controlling   system  used   on 282 

CANOVETTI,  experiment  on   skin   friction 5<j 

CENTER  OF  GRAVITY,  position  of,  discussion 258-260 

CENTER   OF  PRESSURE,  determination   of 61-66 

Center  of  pressure,  position  of  on  flat  planes,   table 62 

Center  of  pressure,  references  to  previous  determinations  of 66 

Center   of   pressure   on   arched   surfaces   various   determinations   of 

center  of   pressure   on 65 

Center  of  pressure,  sudden  movement  of  as  cause  of  accidents....  307-311 

CENTRIPETAL   FORCE,  effect  of  on  accidents 311-317 

CHANUTE,    OCTAVE    10 

CHANUTE,  GLIDERS    11 

CODY    (1909)    BIPLANE,  detailed  description  of. 167 

Cody   (1911)  biplane,  detailed  description  of 171 

COLLISIONS   OF  AEROPLANES,  consideration   of 299-301 

CONTROL,   TRANSVERSE,  comparison  of   various   methods 260-262 

CONTROLLING  APPARATUS,  detailed  description  of  systems  used 279-2DO 

CURTISS  TYPES. 

Curtiss   biplane,    detailed    description   of 174 

Curtiss  biplane,  description  of  controlling  system  used  on 283-284 

Curtiss,    experiments   over    water 320-323 

CURVED  SURFACES. 

See  also  Planes-curved. 


PAGE 

52 


328  INDEX 

Curved  surfaces,  experiments  of  Eiffel   on 

Curved    surfaces,    experiments    of    Prandtl 52 

Curved  surfaces,  experiments  of   Rateau 52 

Curved   surface,   example  of   calculation   of   pressure   by    Lilientlial 

method     47 

Curved    surface,    Lilienthal's    tabie 40 

Curved  surface,  distribution  of  pressure  on GO 

Curved  surface,  effect  of  depth  of  curvature  of  on  lift  and  drift.  .  .  67 

DEFINITION    OF    TERMS 92-9.'{ 

DENSITY  OF  AIR,  effect  of  temperature  on 17 

Density  of  air,  effect  of  altitude  on 18 

DEPTH  OF  CURVATURE,  effect  of  on  lift  and  drift 67-72 

DESIGN   OF  AN  AEROPLANE,  numerical   example  of 75-80 

DIDION,  experiments  of  on  falling  planes 24 

DORNER   MONOPLANE,  detailed  description  of 117 

DRIFT  AND  LIFT,   consideration   of 42 

DUCHEMIN,  COL.,  experiments  on   resistance  of   fluids 24 

Duchemin  formula  for  pressure  on  flat  inclined  plane 88 

DUFAUX    BIPLANE,  detailed   description   of 170 

DUNNE  BIPLANE,  detailed  description  of 182 

EFFICIENCY  OF  AEROPLANES,  discussion  of 270-275 

EIFFEL,   experiments   on   air   resistance 25 

Eiffel,   experiments  on   curved   surfaces 52 

Eiffel,  lift  and  drift  of  curved  plane 72 

Eiffel,   determination   of   position   of  center   of   pressure  on    curved 

planes    64 

Eiffel,  investigation  of  distribution  of  pressure  over  curved  plane.  .  66 

EQUALIZERS,   discussion    of   use   of 260 

ETRICH    MONOPLANE,   detailed   description   of 120 

FARMAN  TYPES. 

Farman,   on   early   Voisin 14 

Farman    (1909)    biplane,  detailed  description  of 187 

Farman   biplane,    (type  Michelin),  detailed  description  of 194 

Farman.  biplane,  description  of  controlling  system  used  on 285-286 

Farman,  Maurice,  biplane,  detailed  description  of 198 

FLAT  INCLINED  PLANE,  action  of  air  stream  on 35-37 

Flat  inclined  plane  at  high  angle  of  incidence,  air  flow  on 42 

Flat  inclined  plane,  numerical  example  of  calculation  of  pressure  on  40 

Flat  inclined  plane,  various  formulae  for  pressure  on 38 

Flat   inclined    plane,   graphical    representation    of  various    formula* 

for    pressure    on 39 

Flat  inclined  planes,  position  of  center  of  pressure  on 61 

FLIGHT,  characteristics  of  for  different  types 276 

Flight,   diagrams  of  various  methods  of 314 

FRICTIONAL  RESISTANCE  OF  AIR 55-59 

Frictional   resistance  of  air,  numerical  example 5G 

FUSIFORM 20 

FUTURE,  probable  use  of  variable  surface,  discussion 317-323 

GLIDERS,   Lilienthal    9 

Chanute     11 

Wright     11 

GOUPY   BIPLANE,  detailed  description   of 203 


INDEX 

PAGE 

GRADE,  MONOPLANE,  detailed  description  of 124 

HAGEN,  experiments  on  air  resistance 24 

HANRIOT  MONOPLANE,  detailed  description  of 127 

Han  riot  monoplane,  description  of  controlling  system  used  on."....  287 

HASTINGS  FORMULA,  for  pressure  on  flat  inclined  planes 38 

INCLINED  PLANE,  flat,  action  of  air  stream  on 35-37 

INCIDENT  ANGLE,  discussion  of  best  value  for 264-267 

Incident  angle,  air  flow  on  flat  inclined  plane  at  high 42 

Inclined  plane,  various  formulae  for  pressure  on  flat 38 

INSTRUCTION  OF  AVIATORS,  Antoinette  machine  for 280 

JOESSEL,  experiments  on  center  of  pressure  on  flat  planes 61 

KEELS,  discussion  of  and  comparison  of  dispositions  used  on  prominent 

types    255-256 

RUMMER,  experiments  of  on  center  of  pressure  on  flat  planes 62 

LAN-CHESTER,   friction    of   air 55 

LANGLEY,    aerodrome,    man-carrying 4 

Langley,    aerodrome,    model 2 

Langley,   aerodrome,   wreck  of 5-6 

Langley,   S.    P.,   experiments   in   areo-dynamics 2 

Langley,  experiments  on  air  resistance 25 

Langley,   results  of  experiments  on  flat  inclined  plane 41 

Langley,   S.  P.,  determination   of  position  of  center  of  pressure  on 

flat   planes    62 

Langley,   S.   P.,  whirling  table 2 

LIFT  AND  DRIFT,  derivation   of 42 

Lift  and  drift,  effect  of  aspect  ratio  on 72-74 

Lift  and  drift  ratio,  Langley 50 

Lift  and   drift,   ratio   of,   Lilienthal 50 

Lift  and  drift,  ratio  of  for  curved  plane 51-53 

Lift  and  drift,  effect  of  depth  of  curvature  on 67-72 

Lift  and  drift  of  curved  plane,  Eiffel  results  on 72 

Lift  to  drift,  ratio  of  for  curved  planes,  Prandtl 77 

Lift  and  drift,  values  of  for  curved  plane,  by  Prandtl 67-74 

LILIENTHAL,   OTTO    7 

Lilienthal,  consideration  of  curved  surfaces 46 

Lilienthal's  table  of  curved  surfaces 49 

Lilienthal's  method  of  calculation  of  pressure,  numerical  example  of  47 

Lilienthal,    O.,    gliding    experiments 8-0 

LOADING,  effect  of  on  flight 272 

Loading,   table  of  values  for  prominent  types 274 

MAXWELL,   experiments  on   air   friction ". 55 

MONOPLANES. 

Monoplanes,   important  types   of 05-150 

Monoplanes,  detailed  diagram  of  notable  types 05-150 

MOTIVE  POWER,  determination  of 85 

Motive  power,   pounds  per  horse-power,   table  of   values  for  promi- 
nent  types    275 

MOTOR,   position    of,    discussion 257 

MOUNTING,  discussion  of  different  types  and  comparison 247-250 

NEALE   BIPLANE,  detailed   description   of . .  . 207 

NEWTON,  ISAAC,  consideration  of  flow  of  air  on  normal  surface 20-21 

Newton,  Isaac,  consideration  of  air  pressure  on  inclined  surface...  36 

NIEUPORT  MONOPLANE,  detailed  description  of 130 


330  INDEX 

PAGE 

OOKLL,  experiments   on  air  friction 55 

PAULHAN  BIPLANE,  detailed  description  of 210 

PFITZNER  MONOPLANE,  detailed  description  of 131 

PISCHOF  MONOPLANE,  detailed  description  of 136 

PLANES. 

Planes,  Aspect  Ratio  of   (see  Aspect  Ratio) 

Plane,  distribution  of  pressure  on 66 

Planes,    curved    46-53 

Plane,  curved  section  chord,  etc.  to  find 46 

Curved  inclined  planes,  pressures  on  Lilienthal 44 

Curved  plane,  von   Dallwitz   formula  for   pressure  on 51 

Curved  inclined  plane,  forces  on 47 

Curved  inclined  plane,  LilienthaPs  values 46 

Curved  plane,  ratio  of  lift  to  drift 51-53 

Curved  plane,  position  of  center  of  pressure  on 64-66 

Plane,  flat  inclined,  references  to  previous  works  on 43 

Plane,  flat  inclined,   pressure  on 35-43 

Plane,  flat  inclined,  air  flow  on  at  high  angle  of  incidence 42 

Plane,  flat  inclined,  numerical  example  of  calculation  of  pressure  on  40 

Plane,  normal,  effect  of  air  stream  on 18 

PRESSURE,  effect  of  on  air  resistance IT 

Pressure  of  air  on   normal  surface,   equation   of *.  22 

See  also  under  Air. 

POLE,  investigation    of  air   friction 55 

POUNDS,   per  horse-power  for  prominent  types 275 

Pounds  per  square  foot  of  surface,  values  of  for  prominent  types.  .  274 
PRANDTL,    determination    of   position    of   center   of   pressure   on    curved 

planes    64 

PRANDTL,  experiments   on   curved  surfaces 52 

Prandtl,  results  of  experiments  on  lift  and  drift  of  curved  planes.  .  67-74 

PRESSURE  OF  AIR,  on  normal  surface 22 

Pressure,    center    of 61-66 

Pressure,  distribution  of  on  curved  plane 66 

PROPELLER,    calculation    of 86-88 

Propeller,  effect  of  position  on  aviator's  comfort 258 

Propellers,   discussion  of   position   of 267-268 

BATEAU,  experiments  on  curved   surface ^ 52 

Rateau,    determination     of    positions     of    center    of    pressure     on 

curved   planes    64 

Rateau,     determination     of     position     of     center    of     pressure     on 

flat   planes    62 

RATIO  OF  PRESSURE  incline  to  pressure  normal,  table 41 

RAYLEIGH  FORMULA  for  pressure  on  flat  inclined  plane 38 

R.  E.  P.  MONOPLANE   (1909),  detailed  description  of 140 

R.    E.    P.,    monoplane  (1911,  one  seat),  detailed  description  of....  145 

RESISTANCE  OF  THE  AIR,  factors  on  which   it  depends 17 

See  also  under  Air. 
See  Air  Resistance. 

RUDDERS,  forces  caused  by  on  aeroplanes 82 

Rudders,    design    of 81-85 

Rudders,    discussion    of 251-254 

ROUSE,   air    resistance 23 

RUSSELL,  experiments  on  air  resistance , .-.  28 


INDEX  331 

PAGE 

Russell,  experiments  on  train  resistance. 28 

SANTOS-DUMONT    14 

Santos-Duniont   monoplane,   detailed  description  of 148 

SCREENS,,  discussion  of  use  of  in  transverse  control 260 

SEATS,,  POSITION  OR,  discussion 250 

Seats,    enclosed,    advantages    of 258 

SHAPES — OF    LEAST    RESISTANCE 20 

SKIDS,  discussion   of  use  of 247 

Skid  and  wheel  combinations,  discussion  of  use  of 247 

SKIN   FRICTION  OF  AIR 55-59 

SMEATON,   JOHN — Table  of  air   pressure 23 

SOMMER   BIPLANE,   detailed   description   of 214 

Sommer    monoplane,    detailed    description    of 151 

SPEED,  values  for  prominent  types,  table 277 

STABILITY,    lateral,    discussion 260-2G2 

STANTON,  experiments  on  air  resistance 20 

STREAM   LINE  FORM 20 

STRUCTURE  OF  AEROPLANES,  weakness  as  cause  of  accidents 305-307 

SURFACE,  loading  per  square  foot,  table  of  values  for  prominent  types.  .  274 

Surface,  suggested  method  of  varying  the  size  in  flight 319-321 

TELLIER   MONOPLANE,   detailed    description    of 153 

TERMINOLOGY,    meaning   of 02-93 

TRANSVERSE  CONTROL,   comparison  of  various  methods 200-262 

VOISIN    (1909)   BIPLANE,  detailed  description  of 218 

Voisin  biplane  (tractor  screw  type)    detailed  description  of 222 

Voisin  biplane   (type  "Bordeaux"),  detailed  description  of 224 

Voisin   biplane   (front  control),  detailed  description  of 229 

WARPING,  discussion   of  use  of 260 

WATER,  action  of  stream  passing  normal  surface 30 

Water,   experiments   over   by   Curtiss 320-332 

WHIRLING  TABLE,  Langley,  S.  P 2 

WRIGHT  BROTHERS,  early   flights  of 12 

Wright  types,  detailed  description  of 230 

Wright   biplane   (model  R),  detailed  description   of 237 

Wright  biplane   (1911)   model  B,  detailed  description  of 243 

Wright  biplane,  description  of  controlling  system  used  on 287-200 

VALKYRIE  MONOPLANE,  detailed   description   of 156 

VOLPLANE,   various   methods 31 4 

VON  DALLWITZ  FORMULA,    for  pressure  of  curved  plane 51 

ZAHM,  experiments  on  air  resistance 20 

Zahm,  determination  of  frictional  resistance  of  air 5G  50 

Zabm,  skin  friction  table 58 

ZOSSEN,  tests  on  train  resistance  of  at  high  speed 29 


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THIS  BOOK  IS  DUE 


ST 


'    • 


APR  *  1942 


dj. 

9Jan'60PW 

JAAK    1350 


.9 


72  -9  AM  6  2 

-L-D  2l-5om.i  f 


•* 


TJ-  l  ?./ 


UNIVERSITY  OF  CAUFORNIA  LIBRARY 


